Updated on 2022/09/25

写真a

 
MIYAGAWA, Kazuyoshi
 
Affiliation
Faculty of Science and Engineering, School of Fundamental Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

  • 2020
    -
    2022

    リサーチイノベ オープンイノベーション推進セクション   兼任センター員

Education

  • 2006.09
    -
    2007.08

    Osaka University   Graduate School of Engineering Science   Department of Mechanical Science and Bioengineering Division of Mechanical Engineering  

  • 1983.04
    -
    1985.03

    Waseda University   Graduate School of Science and Engineering   Mechanical Engineering  

  • 1979.04
    -
    1983.03

    Waseda University   School of Science and Engineering   Mechanical engineering  

Degree

  • OSAKA University   Doctor of Engineering

Research Experience

  • 2020.04
    -
    Now

    Waseda University   Department of Applied Machanics and Aerospace Engineering   Professor   Doctor of Engineering

  • 2012.09
    -
    2020.04

    Waseda University   Department of Applied Mechanics and Aerospace Engineering   Professor   Doctor of Engineering

  • 2011.09
    -
    2012.08

    Waseda University   Department of Applied Mechanics and Aerospace Engineering   Associate Professor   Doctor of Engineering

  • 1985.04
    -
    2011.08

    Mitsubishi Heavy Industries, Ltd.   Technical Headquaters

Professional Memberships

  • 2020.10
    -
    Now

    Japan Wind Energy Association (JWEA)

  • 2018.07
    -
    Now

    ASME

  • 2018.04
    -
    Now

    IAHR

  • 2018.03
    -
    Now

    航空宇宙学会

  • 2016.04
    -
    Now

    GTSJ

  •  
     
     

    International Electrotechnical Commission

  •  
     
     

    Turbomachinery Society of Japan

  •  
     
     

    The Japan Society of Mechanical Engineers

▼display all

 

Research Areas

  • Fluid engineering

Research Interests

  • Fluid Machinery, Fluid Engineering, Cavitation, Flow Induced Vibration

Papers

  • Investigation on the impeller-diffuser interaction on the unstable flow in a mixed-flow pump using a modified partially averaged Navier-Stokes model

    Weixiang Ye, Chen Geng, Akihiro Ikuta, Shinya Hachinota, Kazuyoshi Miyagawa, Xianwu Luo

    Ocean Engineering   238  2021.10  [Refereed]

     View Summary

    In this paper, the effect of the impeller-diffuser interaction on the unstable flow in a mixed-flow pump operating under one part-load condition is investigated based on the local energy loss analysis using a modified SST k-ω partially averaged Navier-Stokes (MSST PANS) model. The comparison on the pump performance shows a good agreement between the experiment and simulation. The characteristic curve of the test pump presents a positive slope region, where hydraulic loss increases 90.75% in the impeller and 16.75% in the diffuser. The internal flow analysis depicts that the rotating stall evolution captured in the impeller passages involves larger energy transfer while the separating flow in the diffuser passage involves lower energy transfer. As the impeller blade tailing edge (TE) begins to interact with the diffuser blade leading edge (LE), the vortex attached to the impeller blade TE is cut off into two parts, one of which keeps propagating circumferentially and forms the rotating stall in the impeller, and the other is regarded as the shedding vortex, moving into the diffuser. Further analysis by the Fast Fourier Transform and proper orthogonal decomposition reveals the frequency of rotating stall is 1.49fn, and the frequency of the shedding vortex is 0.53fn.

    DOI

  • Design of experiments applied to francis turbine draft tube to minimize pressure pulsations and energy losses in off-design conditions

    Arthur Favrel, Nak Joong Lee, Tatsuya Irie, Kazuyoshi Miyagawa

    Energies   14 ( 13 )  2021.07  [Refereed]

    Authorship:Last author

     View Summary

    This paper proposes an original approach to investigate the influence of the geometry of Francis turbines draft tube on pressure fluctuations and energy losses in off-design conditions. It is based on Design of Experiments (DOE) of the draft tube geometry and steady/unsteady Computational Fluid Dynamics (CFD) simulations of the draft tube internal flow. The test case is a Francis turbine unit of specific speed Ns = 120 m-kW which is required to operate continuously in off-design conditions, either with 45% (part-load) or 110% (full-load) of the design flow rate. Nine different draft tube geometries featuring a different set of geometrical parameters are first defined by an orthogonal array-based DOE approach. For each of them, unsteady and steady CFD simulations of the internal flow from guide vane to draft tube outlet are performed at part-load and full-load conditions, respectively. The influence of each geometrical parameter on both the flow instability and resulting pressure pulsations, as well as on energy losses in the draft tube, are investigated by applying an Analysis of Means (ANOM) to the numerical results. The whole methodology enables the identification of a set of geometrical parameters minimizing the pressure fluctuations occurring in part-load conditions as well as the energy losses in both full-load and part-load conditions while maintaining the requested pressure recovery. Finally, the results of the CFD simulations with the final draft tube geometry are compared with the results estimated by the ANOM, which demonstrates that the proposed methodology also enables a rough preliminary estimation of the draft tube losses and pressure fluctuations amplitude.

    DOI

  • Effect of modified draft tube with inclined conical diffuser on flow instabilities in Francis turbine

    Xing Zhou, Changzheng Shi, Kazuyoshi Miyagawa, Hegao Wu

    Renewable Energy   172   606 - 617  2021.07  [Refereed]

     View Summary

    When a Francis turbine operates over an extended range of regimes far from the best efficiency point, the formation of a helical precessing vortex rope can lead to reduced efficiency, severe pressure fluctuations, and power swings. Because the existence of a vortex rope limits the operating range of the Francis turbine, it is necessary to adopt certain measures to mitigate the occurrence of vortex ropes and the associated pressure fluctuations, to improve the operating flexibility of the turbine. In the present study, a novel method to mitigate vortex ropes was proposed. This method involves using a modified draft tube with an inclined conical diffuser. Under the operating condition of a 16° Guide Vane Opening, four different inclination angles (from 0° to 24.4°) were investigated to determine the optimal inclination angle. Computational fluid dynamics results demonstrated that an inclination angle of 18.8° was the most effective for hindering the development of strong swirling flow and resulted in a decline in the pressure pulsation amplitude. This angle was later used under three other partial load operating points, and the results were compared with those of a traditional draft tube. The modified draft tube with an inclined conical diffuser exhibited satisfactory and stable performance in terms of reducing the flow instabilities within the draft tube. Based on an analysis of the mechanism for alleviation of the vortex rope, it was concluded that the inclined conical diffuser plays an effective role in reducing the swirling flow in the draft tube and thus destroying the development of the vortex rope. As a result, the proposed approach could be adopted to ameliorate the instability issue in Francis turbines.

    DOI

  • Numerical and experimental analysis of pressure fluctuations in the draft-tube of a Francis turbine using the swirl number

    M. H. Khozaei, A. Favrel, T. Masuko, N. Yamaguchi, R. Watanabe, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   774 ( 1 )  2021.06  [Refereed]

    Authorship:Last author

     View Summary

    Pressure fluctuations in the draft-tubes of hydraulic turbines are the most dominant issues that may cause damages to a hydraulic power plant. When the frequency of the fluctuations coincides with one natural frequencies of the plant, resonance with high amplitude vibrations and pressure pulsations occurs, dramatically impacting the integrity of the plant. This research focuses on the part-load behaviour of a medium specific-speed Francis turbine (with specific speed 184 m.kW), designed by the authors in the framework of an industrial project. This paper combines the results of model tests with CFD simulation to investigate the part-load behaviour of the turbine. To do so, performance of the turbine is numerically simulated at one operating condition by solving the RANS equations via the commercial code ANSYS CFX 19.0. The k-ω SST turbulence model is used to predict the turbine performance. In addition, model tests are conducted in the range of 20% to 110% guide vane opening. To capture pressure fluctuations in the draft-tube, 12 static pressure sensors are installed in 4 different sections of the draft-tube. The no-swirl and other iso-swirl lines of the draft tube flow are first determined by using CFD results. Furthermore, pressure signals from model tests are analysed by performing cross spectral density analysis. Two transitions in the behaviour of the precessing vortex under part-load conditions occurring at given values of swirl number are observed. Finally, it is observed that linear correlations between the Strouhal number of the vortex rope frequency and the swirl number can be established within the 2nd and 3rd part-load regimes, independently of the values of the speed coefficient.

    DOI

  • Dynamic behaviour of a full-load cavitation vortex in a Francis turbine draft tube excited at its eigenfrequencies

    A. Favrel, E. Vagnoni, J. Gomes Pereira, M. Sakamoto, K. Yamaishi, A. Müller, F. Avellan, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   774 ( 1 )  2021.06  [Refereed]

    Authorship:Last author

     View Summary

    The operating range of Francis turbines is limited at full-load conditions by the formation of a cavitation vortex rope that may enter self-oscillations under certain conditions. This induces severe pressure pulsations in the entire system, as well as output power swings putting at risk the integrity of the electro-mechanical components. The understanding of the underlying physical mechanisms and the prediction of the stability of hydropower units at full-load conditions are therefore crucial to ensure a safe extension of their operating range. In the present paper, the dynamic behaviour of a stable cavitation vortex rope at full load is investigated by high-speed visualizations while the test rig is excited at its first and second hydroacoustic eigenfrequencies. It is first demonstrated that the cavitation volume and the pressure in the draft tube are more likely to oscillate at the first eigenfrequency, in agreement with the observations of self-excited oscillations at the first eigenfrequency of the cavitation vortex rope during unstable full-load conditions. In addition, it is observed that the amplitude of both the cavitation volume and pressure fluctuations in the draft tube reach a limit value when the amplitude of the excitation is further increased. Further investigations will determine if this behaviour can be generalized to any full-load conditions and will focus on the determination of the hydro-acoustic parameters of the draft tube cavitation flow based on the behaviour of the vortex rope during forced oscillations.

    DOI

  • Development of Low-Specific Speed New-Type Hydraulic Turbine Equipped with Volute: Numerical Investigation and Performance Prediction

    T. Irie, W. Takahashi, K. Miyagawa, T. Sugimoto, T. Naganuma, R. Waku

    IOP Conference Series: Earth and Environmental Science   774 ( 1 )  2021.06  [Refereed]

     View Summary

    With the goal of broadening the operation range of hydraulic turbines, we propose a new-type hydraulic turbine in our research. The new turbine has no draft tube, but instead is equipped with a parallel diffuser and a volute, i.e. a radial vaneless diffuser and a spiral discharge collector, respectively. In this research, we carried out a CFD investigation on specific speed 77 [m-kW] prototype turbine to predict its performance. The simulation results showed that under large discharge there is a high risk of cavitation or pressure fluctuation. In this condition, the amplitudes of the pressure fluctuation are 0.6 percent and 1.3 percent of the effective head, on the volute wall and the parallel diffuser wall, respectively. The possibility of flow instabilities such as a vortex rope precession and a rotating stall to occur is small enough to keep operating the turbine at both deep part-load and full load. The final design of the turbine has been decided based on this investigation. The turbine verification tests are going to start in early 2021.

    DOI

  • Numerical simulation of the unsteady cavitating flow in a Francis turbine draft tube at Upper-Part-Load (UPL) conditions

    Z. Liu, A. Favrel, W. Takahashi, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   774 ( 1 )  2021.06  [Refereed]

     View Summary

    At part-load conditions, Francis turbines experience the development of a precessing vortex rope in their draft tube (DT), rotating with a frequency between 0.2 and 0.5 times the runner frequency. It induces pressure pulsations at the precession frequency in the whole hydraulic system, undesirable vibrations and noise putting at risk the stability of the system and the lifetime of the machine components. In specific machines, a dramatic amplification of the noise and vibrations can be observed between 70% and 85% of the design conditions. In these cases, synchronous pressure pulsations with a high frequency, typically between 2 and 4 times the runner frequency, are observed, referred to as the so-called Upper-Part-Load (UPL) pulsations. These pulsations are induced by a self-excitation of the entire hydraulic system including the cavitation vortex rope at one of its high order eigenmodes. Besides, the cavitation vortex rope features an elliptical cross-section rotating around the vortex axis at a high frequency. In this manuscript, unsteady two-phase flow simulations using a Scaled-Adaptive-Simulation (SAS) turbulence model and ZGB cavitation model of a Francis turbine draft tube at 80% of the design condition are performed to clarify the mechanisms responsible for the formation of the elliptical shape of the vortex and the UPL pulsations. However, the numerical simulation with a constant inlet boundary condition cannot reproduce the UPL pulsation phenomenon since it is a self-excited oscillation at one eigenmode of the complete system, which is not considered. Therefore, the UPL pulsations component is extracted from the measured pressure fluctuations data by applying a band-pass filter and is then set as the inlet boundary condition in the numerical simulation. The flow field is therefore artificially excited which aims to confirm whether the same phenomenon can be observed and to compare with the flow field obtained with constant inlet boundary condition. The numerical simulations are validated by experimental results, and the wave propagation in the DT is clarified.

    DOI

  • Investigation on the effect of forward skew angle blade on the hump characteristic in a mixed flow pump using modified partially averaged Navier-Stokes model

    Weixiang Ye, Akihiro Ikuta, Yining Chen, Kazuyoshi Miyagawa, Xianwu Luo

    Renewable Energy   170   118 - 132  2021.06  [Refereed]

     View Summary

    A mixed flow pump is regarded as an important power facility in the hydropower field for renewable energy. Pump impeller design shows a great attempt to alleviate the hump characteristic and suppress the severe pressure fluctuations as the mixed flow pumps operate under part-load conditions. In this respect, an advanced turbulence model, i.e., modified SST k-ω partially averaged Navier-Stokes (MSST PANS) model, was adopted to numerically investigate the effect of forward skew angle blade on the hump characteristic using different impeller blades. Both experimental and numerical results indicate that the pump with forward skew angle blade shifts the hump region to the deeper part-load region. In the pump impeller with the forward skew angle blades, a synchronous stall cell is observed near the blade leading edge and near the hub side, while typical rotating stall cell evolution is observed in the conventional pump impeller. Analysis on the blade loading also indicates that under the unstable condition, the forward skew angle blade could switch the mid-loaded distribution to the fore-loaded distribution. Finally, the low frequency pressure fluctuations induced by the rotating stall cell evolution could be also eliminated successfully as the forward skew angle impeller blades are adopted.

    DOI

  • Design Optimization of High Specific Speed Prototype Francis Turbine by Design of Experiments

    Nak Joong Lee, Young Cheol Hwang, Morihito Inagaki, Kazuyoshi Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05  [Refereed]

    Authorship:Last author

     View Summary

    In general, Francis turbines are known to last for 40 to 50 years of use. However, exchanging an old turbine for a new is expensive because of modernization costs. Therefore, many modernization projects will take place through new runner changes. The Francis turbine in this paper has a high specific speed of about 330m-kW and a runner diameter of about 4.3m. The new runner can be expected to have a more stable flow and improved performance by flow analysis. In this paper, the performance analysis of the runner was performed using the CFD by Design Of Experiments (DOE). The sensitivity of variables was examined using L18 method. Numerical analysis was performed via BladeGen, Turbogrid, ICEM CFD, and CFX, which are commercial CFD codes. The design goal is to enable not only the best efficiency point but also a more stable operation than before even at partial load conditions. Find out how to find the shape of a runner blade by searching for design points that maximize annual power generation according to newly selected operating conditions.

    DOI

  • A modified partially averaged Navier-stokes model for the turbulent flows over a backward facing step

    W. X. Ye, K. Miyagawa, X. W. Luo

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05  [Refereed]

     View Summary

    In current study, a partially averaged Navier-stokes model based on a modified SST k-? model is proposed (MSST PANS) to predict the turbulent flows with flow separations, recirculation and reattachment. A benchmark case, turbulence flows over the backward facing step (Re=50000), is treated to evaluate the capacity of the MSST PANS model. Several other turbulence models, i.e., the standard k-? model, SST k-? model, the standard k-? PANS (SKE PANS) model and SST k-? PANS (SST PANS) model are also implemented for comparisons with some available experimental data. Results show that the MSST PANS model performs the closest results in predicting the reattachment length as well as the corner vortex. Furthermore, the MSST PANS model yields improved statistics on the skin frictions, pressures, velocity profiles together with Reynolds stresses. In contrast to the SST PANS models, the modifications on the eddy viscosity and ? equation with consideration of streamline curvature show promising in capturing the small-scale flow separations, recirculation and reattachments in some industrial applications.

    DOI

  • Effect of Pulsating Flow on Surge Frequency of a Turbocharger Compressor

    Y. Asanaka, K. Kobayashi, M. Sakakibara, Y. Itagaki, Y. Nakamura, K. Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    Turbocharger compressors operate under pulsating flow due to continuous opening and closing of engine valves placed downstream of the compressor but exhibit a hysteresis loop deviating from steady characteristics. As the flow in a compressor is throttled, both pressure and flow discharge unstably oscillate. The instability is known as surge and it affects not only the compressor itself but also its whole engine-turbocharger system. For estimating the stable operation range, partial flow tests of a turbocharger compressor under pulsating flow were conducted. Using a compressor test apparatus with a pulsating flow generator and a tank whose capacity can be changed, the flow rate was controlled by a valve. Under steady flow, surge hysteresis loops caused by oscillating pressure and flow rate were obtained in each rotational speed. By Fast Fourier Transform (FFT) of pressure signals, the occurrence of surge with different frequencies was confirmed depending on the tank capacity. Next in pulsating flow tests, a compressor rotational speed is fixed, and pulsating frequencies given by the pulsating flow generator are changed. The obtained surge frequencies were different from those in steady flow tests. Especially, it is likely to be drawn to the frequency that is equal, two times and a half rate of the pulsating frequency. Numerical computation with one-dimensional calculation is conducted to investigate such a phenomenon.

    DOI

  • Optimization procedure to design a Francis turbine runner using 2D Through-flow analysis

    Ryo Watanabe, Kazuyoshi Miyagawa, Mohammad Hossein Khozaei, Naoki Yamaguchi, Toshitake Masuko

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    Due to increasing usage of Feed-in Tariff (FIT), which is a subsidy system to encourage expansion of renewable energy and to reduce costs associated with introduction of renewable energy, demand for hydraulic turbine designers has increased solely for the purpose of improving turbine performance. With these requirements, CFD simulation is a powerful tool for designers to improve the internal flow and pressure distribution in turbines. Traditionally, most designers use a trial-and-error process based on previous experience to design new turbines. Usually, achieving the goal is a lengthy and painstaking process. This paper proposes a novel method which combines both CFD and optimization methods to automatically optimize a Francis turbine. This procedure includes four components: a design program, a CFD solver, a scheduler, and an optimization algorithm. This paper describes an attempt to automatically optimize a Francis turbine runner by using ANSYS Vista TF as the 2D CFD solver based on through-flow theory, and ANSYS CFX 19.1 as the 3D CFD solver based on Finite Volume Method (FVM). The runner geometry is parameterized by Bezier curves in the design program. CFD analysis is performed to assess the efficiency of the runner, and also the output power is calculated by runner torque. These two parameters are used as the objective function of the optimization algorithm. This method is used to optimize the runner geometry, which consists of two parts: the meridional plane and profile camber lines. We confirmed that the new turbine, which was optimized by the above-mentioned method, has better efficiency than the existing one.

    DOI

  • Mitigation Method for Pressure Fluctuations Induced by Acoustic Resonance

    K. Tsutaya, Z. Liu, M. Kubo, K. Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    Multi-stage pumps used for boiler water supply of thermal power plants have large capacity and pressure. Fluctuations may cause vibration and noise in pumps, piping systems, and surrounding structures. Lots of studies have been conducted on the pressure fluctuation phenomenon of turbopump piping systems. Some of the factors are the rotor-stator interaction, a resonance between the fluid in the pipe and, excitation source and resonance between structure and pump operation. Besides, studies on mitigation method for pressure fluctuations have been conducted. Inserting orifice to add damping, adjusting the length of pipe to change resonance frequency and, installing resonator to mitigate a specific frequency. However, these studies have not quantified the solution to the pressure fluctuations, so further research is needed to elucidate the causes and establish countermeasures quantitatively. In this study, pressure fluctuations due to acoustic resonance are generated by using a speaker. An orifice, a bent tube, and a branch pipe are installed at the node and antinode of the secondary pressure standing wave in the pipe, and the effects on the standing wave are observed. Moreover, the mitigation method for the pressure standing wave is established by performing a sweep test. Numerical analysis is conducted by AMESim to validate the results of experiment. It is clarified that by inserting the orifice at the appropriate position of a standing wave, pressure fluctuations are mitigated. In the case of branch pipe, pressure fluctuations are effectively mitigated by inserting it having appropriate pipe length and boundary condition.

    DOI

  • Influence of Forward Skew Blade Angle on Positive Slope Characteristics of Mixed Flow Pumps

    Akihiro Ikuta, Naruki Nitta, Kazuyoshi Miyagawa, Yasushi Shinozuka, Shigeyuki Tomimatsu

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    Under the part-load conditions, the flow instability in a mixed-flow pump could lead to strong pressure fluctuations and vibrations, posing a great threat to the safety of the system. The current paper investigates effect of the forward skew blade angle on the positive slope characteristic in a high specific speed mixed flow pump using Reynolds averaged Navier-Stokes (RANS) equations coupled with the SST k-? model. The simulation results are compared with the experimental data and show good accordance. In the present study, five types of the mixed-flow pumps with different skew blade angles are prepared based on the conventional pump. It is found that with the increasing of the skew angle, the positive slope region becomes wider and moves towards a deeper part-load region. Further investigations are carried out by calculating the impeller head. Results depict that compared with the dynamic pressure head H d, the static pressure head H st plays more significant role in the formulation of the positive slope characteristic (PSC). Besides, the relative static pressure head H rel drops dramatically while the pump operates under the positive slope region, which matches with the pump performance well. Finally, analysis on the spanwise velocity profiles are further investigated in this paper, and results indicate that the flow accumulated near the impeller hub is one of the reasons to alleviate the head drop and shift the positive slope region to a deeper part-load condition.

    DOI

  • Investigation of Internal Flow in Centrifugal Pump Diffuser using Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics

    Daisuke Sugiyama, Asuma Ichinose, Tomoki Takeda, Kazuyoshi Miyagawa, Hideyo Negishi, Atsuhiro Tsunoda

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    An unshrouded impeller is being developed for high head pumps to reduce costs and disk friction losses. On the other hand, research of internal flow in a diffuser did not clearly reveal flow structure. In this experiment, we measured the velocity distribution at the diffuser inlet and outlet plane using laser doppler velocimetry (LDV) to capture the flow from the unshrouded impeller. The relation between the total pressure and velocity distribution was evaluated. The circumferential velocity and meridian velocity were measured by short-focus LDV (Diode Laser, 74mW) about the circumferential and the height direction of the vane direction. Operating conditions in this steady measurement are at the design point flow rate. The result was compared with computational fluid dynamics (CFD) simulations carried out in steady conditions at the previously defined operation points. In this experiment, a phenomenon that the streamline moved toward the shroud side was confirmed. There was also a region where the static pressure increased on the shroud side at the diffuser inlet. This phenomenon was caused by the influence of the tip leakage flow of the unshrouded impeller downstream and the gap of the impeller's main plate. Furthermore, two high velocity regions on the hub and shroud side at the diffuser outlet were observed because of the secondary flow in the diffuser. From the above studies, it was clarified that the ununiform flow in the diffuser was caused by the influence of the secondary flow in the unshrouded impeller.

    DOI

  • Characteristics of fluid exciting force due to blade row interaction of a propeller turbine

    Ryosuke Mori, Kazushi Ajiro, Kazuyoshi Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    As the use of renewable energy is promoted, much researches on propeller-type turbines are carried out. To improve reliability, it is important to evaluate the fluid exciting force due to blade row interaction that may cause vibration or fatigue fracture. In this paper, CFD(URANS) simulations and experimental studies were conducted to understand the characteristics of the fluid exciting force due to blade row interaction of a propeller turbine. To evaluate the fluid exciting force, strain gauges and pressure sensors were used in the closed-loop water channel. The fluid exciting force acting on the rotor due to the stator was measured by changing stator load type and the rotor-stator distance. Based on the difference in the attenuation tendency of potential interaction and wake interaction due to changes in the rotor-stator distance, the influences of these interactions could be distinguished. As results of experiments and computation, wake interaction affecting pressure fluctuation was hardly attenuated due to the swirling flow and changing the rotor-stator distance has little effect on the attenuation of blade row interaction.

    DOI

  • Influence of engine torque fluctuations on performance characteristics of pumps mounted on vehicles

    Takuma Kawahara, Hideaki Takamiya, Hitoshi Motono, Yasuhiro Hotta, Kazuyoshi Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    A fire pump mounted on the fire engine is driven by a car engine. The engine has plurality of combustion chambers and converts the reciprocating motion of the pistons into rotational motion while shifting the combustion timing of each combustion chambers. When the force generated by the combustion is converted into torque, periodic torque fluctuation is generated. Torque fluctuation finally generates the rotation fluctuation. We analyzed pump performance by the rotation with the sinusoidal fluctuation for the impeller. From the viewpoint of torque and total head, each variable fluctuated in the same phase, but it was confirmed that there was a difference in fluctuation range. With engine rotation fluctuation given to the pump, we verify the pressure characteristics and efficiency on the outlet side change by CFD. In this paper, therefore, we report the results of CFD on pump output characteristics when periodic rotational fluctuations occur due to unsteady torque characteristics of the engine.

    DOI

  • Preface

    Kazuyoshi Miyagawa

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

    DOI

  • Development of turbocharger engine system using 3D and 1D simulation to achieve 50% brake thermal efficiency

    Yohei Nakamura, Kazuyoshi Miyagawa, Yasuo Moriyoshi, Tatsuya Kuboyama

    Journal of Physics: Conference Series   1909 ( 1 )  2021.05

     View Summary

    In recent years, automobile exhaust gas regulations have become stricter due to environmental problems such as global warming. A project by the Cabinet Office called the Strategic Innovation Promotion Program (SIP) began in 2014. SIP has 11 themes in total. One of them, innovative combustion technology, aimed to improve the thermal efficiency of automobiles from the existing 40% to 50%. To improve the thermal efficiency of the automobile, it was essential to improve the efficiency of the turbocharger. In this study, we developed a turbocharger for gasoline and diesel engines. First, to confirm the efficiency of the conventional turbocharger, experiments and CFD analysis of a commercial turbocharger were performed. ANSYS-CFX was used as a numerical code. To confirm the accuracy of the CFD, the CFD results were compared with the experimental results, and it had good agreement with the experimental results. From the analysis results, the loss region of the conventional turbocharger was clarified. The designed turbocharger compressor was tested as a prototype compressor. The results of the compressor had good agreement with CFD results, so it was confirmed that the accuracy of CFD and design method was valid. Finally, A one-dimensional simulation using GT-Power which is a system analysis software for automobiles was performed to evaluate the developed turbocharger on the engine. In the fifth year of the project, the target efficiency of 50% was achieved.

    DOI

  • Prediction of a turbocharger performance under pulsating flow by construction of an unsteady one-dimensional flow analysis model

    Yohei Nakamura, Manato Chinen, Masamichi Sakakibara, Yuudai Abe, Kazuyoshi Miyagawa

    International Journal of Fluid Machinery and Systems   13 ( 4 ) 743 - 749  2020.10

     View Summary

    In recent years, because of the energy crisis, improving the thermal efficiency of automobiles has become a very important issue. It is known that a pulsating flow generated by engine valves affects the performance and efficiency of the turbocharger adversely [1]. However, the turbocharger characteristics under pulsating flow have not been clarified to a satisfying degree yet, and no prediction method of turbocharger performance has been established yet. In this study, an unsteady one-dimensional flow model of a turbocharger is constructed by modeling the physics of aerodynamic loss and unsteady characteristics based on experiments and 3D-CFD. Furthermore, the characteristics of the turbocharger under pulsating flow were predicted using the built one-dimensional unsteady flow model. Moreover, this one-dimensional model was implemented in GT-Power which is a one-dimensional commercial code used by many automobile companies.

    DOI

  • Enhancing effect of an open pipe exit on the precessing vortex core occurring in confined swirling flows

    Arthur Favrel, Zhihao Liu, Kazuyoshi Miyagawa

    EXPERIMENTS IN FLUIDS   61 ( 10 )  2020.09

     View Summary

    This paper investigates the effect of an open pipe exit on the dynamic behaviour of the helical precessing vortex core (PVC) occurring in a confined swirling flow after vortex breakdown. This is achieved by carrying out extensive particle image velocimetry and dynamic pressure measurements downstream of an air swirling flow generator in two pipes configurations at two values of swirl number S = 0.7 and S = 1.1. The first pipe configuration features a diffuser followed by a straight pipe and an open exit. In the second configuration, the open exit is placed closer to the outlet of the swirl generator by removing the straight part. In both configurations, the PVC structural parameters are properly determined by phase-averaging of the instantaneous velocity fields. In the first configuration, a sudden change in the pitch of the helical vortex is observed at both swirl number values downstream of the connection between the diffuser and the straight part. Beyond this transition, the vortex trajectory starts widening as it is getting closer to the open exit of the pipe. The results in the second configuration confirm this enhancing effect of the open exit on the PVC: at both swirl numbers, the vortex trajectory is strongly widened and its radius continuously increases from the swirl generator outlet to the pipe exit, resulting in an increase in the Strouhal number and pressure fluctuations amplitude by 20% and a factor up to 9, respectively, compared with the first configuration. Finally, based on a dimensional analysis, a linear relation between two dimensionless parameters including the vortex parameters and the pressure fluctuations amplitude is derived and supported by the data obtained in both pipe configurations.[GRAPHICS].

    DOI

  • Radial turbine optimization under unsteady flow using nature-inspired algorithms

    Seyedmajid Mehrnia, Kazuyoshi Miyagawa, Jin Kusaka, Yohei Nakamura

    AEROSPACE SCIENCE AND TECHNOLOGY   103  2020.08

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    This paper investigated the performance of a radial flow turbine by coupling metaheuristic algorithms with Computational Fluid Dynamics. We performed the optimization of the casing and wheel of the turbine simultaneously. The computer codes of four metaheuristic algorithms, namely the Genetic Algorithm, Flower Pollination Algorithm, Grey Wolf Optimizer, and the Grasshopper Optimization Algorithm were developed using MATLAB. The optimization results indicated that Grey Wolf Optimizer is the most powerful algorithm to achieve a higher temperature drop in comparison with other algorithms. Revealed by the study, choosing the best angle at the blade inlet is the most influential factor for efficiency improvement. Besides, casing optimization has a positive effect on the pressure recovery of the turbine by eliminating swirling flow. A comparison of the physics of fluid in the optimized and base wheel showed that the flow is more attached to the optimized blade since the backward-facing step produces a favorable pressure gradient mainly in the recirculating bubble. Employing pulsating flow confirmed that the efficiency of the optimized turbine has a significant increase in comparison to the base turbine by more than 2% in high mass flow rates. (C) 2020 Elsevier Masson SAS. All rights reserved.

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  • Investigation of Pressure Fluctuation and Pulsating Hydraulic Axial Thrust in Francis Turbines

    Xing Zhou, Changzheng Shi, Kazuyoshi Miyagawa, Hegao Wu, Jinhong Yu, Zhu Ma

    ENERGIES   13 ( 7 )  2020.04

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    Under the circumstances of rapid expansion of diverse forms of volatile and intermittent renewable energy sources, hydropower stations have become increasingly indispensable for improving the quality of energy conversion processes. As a consequence, Francis turbines, one of the most popular options, need to operate under off-design conditions, particularly for partial load operation. In this paper, a prototype Francis turbine was used to investigate the pressure fluctuations and hydraulic axial thrust pulsation under four partial load conditions. The analyses of pressure fluctuations in the vaneless space, runner, and draft tube are discussed in detail. The observed precession frequency of the vortex rope is 0.24 times that of the runner rotational frequency, which is able to travel upstream (from the draft tube to the vaneless space). Frequencies of both 24.0 and 15.0 times that of the runner rotational frequency are detected in the recording points of the runner surface, while the main dominant frequency recorded in the vaneless zone is 15.0 times that of the runner rotational frequency. Apart from unsteady pressure fluctuations, the pulsating property of hydraulic axial thrust is discussed in depth. In conclusion, the pulsation of hydraulic axial thrust is derived from the pressure fluctuations of the runner surface and is more complicated than the pressure fluctuations.

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  • Numerical simulation on role of the rotating stall on the hump characteristic in a mixed fl ow pump using modi fi ed partially averaged Navier-Stokes model

    Weixiang Ye, Akihiro Ikuta, Yining Chen, Kazuyoshi Miyagawa, Xianwu Luo

    RENEWABLE ENERGY   166   91 - 107  2020.04

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    Insufficient understanding of flow instability interaction between hump characteristic and the rotating stall is a major problem in the application of mixed flow pumps. In this paper, the unsteady flow characteristics of a mixed flow pump are studied numerically to understand the hump characteristic generating mechanism using a modified SST k -u partially averaged Navier-Stokes (MSST PANS) model. The predicted pump characteristic curves show good agreement with experimental data. Fundamental results on time-averaged flow pattern and energy loss distributions depict that the substantial rise of energy loss in the pump impeller is the main reason for the hump characteristic. Detailed flow structures show the peak regions of circumferential vorticity (Uq) and boundary vortex flux (BVF) are located at the blade tip near the trailing edge (TE) and leading edge (LE). Further analysis on the flow angle and blade loading are carried out. The results indicate that the peak region located near the LE of spanwise = 0.8 and streamwise = 0.3 is the source of the rotating stall evolution. In this process, the substantial reduction in the blade loading occurs near the LE, eventually induces the head drop. Finally, pressure fluctuations analysis depicts that low-frequency signal is observed induced by the rotating stall evolution. (C) 2020 Published by Elsevier Ltd.

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  • Visualization of the elliptical form of a cavitation vortex rope and its collapse by two cameras

    A. Favrel, Z. Liu, W. Takahashi, T. Irie, M. Kubo, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   405 ( 1 )  2019.12

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    This article presents preliminary results of an experimental study of the upper-part load instability and the associated elliptical form of the cavitation vortex rope in a Francis turbine draft tube. The influence of the operating parameters on the onset and the development of the instability is first briefly studied by pressure measurements in the draft tube. Visualizations of the cavitation vortex rope and its associated elliptical form are performed by using two synchronized high-speed cameras spaced by an angle of 90°. This allows to reconstruct the instantaneous position of the vortex center along the draft tube. It is confirmed that using a single camera leads to biased estimations of the cavitation volume fluctuations. The breathing behaviour of the vortex rope, responsible for the pressure pulsations according to several authors, cannot be definitely demonstrated without a proper reconstruction of the vortex shape based on high-speed videos from several positions. Finally, unique intermittent collapses of cavitation in the vortex center, giving rise to two distinct cavities connecting on both sides the vortex rope, are highlighted.

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  • Influence of forward rake and skew blade angle on positive slope characteristics of mixed flow pumps

    N. Nitta, S. Maeda, H. Kanno, K. Miyagawa, Y. Shinozuka, K. Kado, S. Tomimatsu

    IOP Conference Series: Earth and Environmental Science   240 ( 3 )  2019.03

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    In many of the mixed flow pumps that have been studied in the past, the impeller has a sweepback wing. Especially, the positive slope characteristics have been studied to operate pump in a stable regime. The cause of the positive slope in the characteristic curve of the mixed flow pump is the reverse flow, with the turning becomes stronger, at the leading edge of the blade tip side in the flow rate range. Also, at the flow rate at which the slope of the characteristic curve becomes positive, the angular momentum becomes negative at the leading edge of the impeller, and the work amount sharply decreases at the leading edge more than the work amount increase at the trailing edge so the angular momentum decreases. However, the influence of the forward rake and skew blade on the performance, the positive slope characteristics, and the internal flow have not been studied much. In this study, we designed and analysed a forward rake and skew blade mixed flow pump. About the forward rake and skew blade, we found the cause of the positive slope characteristics is the same reason as the sweepback wing, but the flow rate range of occurrence of the positive slope characteristics was lower in the forward rake and skew pump than in the sweepback pump.

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  • Proposal of a new hydraulic turbine capable of high efficiency operation over a wide range of flow rate and effective head

    T. Irie, W. Takahashi, M. Shinji, K. Miyagawa, T. Sugimoto, T. Naganuma, R. Waku

    IOP Conference Series: Earth and Environmental Science   240 ( 2 )  2019.03

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    Hydraulic turbines should keep a high efficiency in the widest range of operation conditions. However, conventional turbine has been designed to reduce swirl at a runner outlet at its design point to maximize efficiency, and is unsuitable for partial load operation due to the growth of swirl at the outlet. The swirl of the runner outflow causes loss and unstable flow at the downstream draft tube. To prevent those problems, we developed a new type of hydraulic turbine capable of a wide range of operation conditions, specifically flow rate and effective head, with a high efficiency. The designed new turbine is equipped with a parallel diffuser and a volute diffuser downstream of the runner, instead of a draft tube. The outflow swirl is arranged to have forward turning constantly against runner rotation. It is possible to decrease downstream loss, and to mitigate the vortex core behaviour this way.

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  • Characteristics and internal flow of a low specific speed pump used as a turbine

    Z. H. Liu, T. Yukawa, K. Miyagawa, T. Fahimi, M. Tahani

    IOP Conference Series: Earth and Environmental Science   240 ( 4 )  2019.03

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    PAT (Pump as Turbine) has gradually been a popular solution for the small-scale hydropower generation. Because of the rich assortment and the low initial investment. However, PAT is designed as a pump but not a turbine. Therefore, a lot of research was conducted about the performance prediction and the loss distribution of pump and turbine mode. In this paper, we focused on the internal flow and loss mechanisms of the best efficient point of both modes. The characteristic and internal flow were investigated by experimental and computational approaches. The reasons of efficiency reduction in turbine mode and loss mechanisms were clarified by the computational results. The separation flow region occurs on the suction side or pressure side in non-BEP, and the swirling flow counter-rotates the PAT occurring at the outlet in BEP might be the reasons of the efficiency reduction. Moreover, because of the camber line shape of PAT, the separation flow occurs near the inlet could not reattach soon which induces the loss region. Furthermore, the secondary flow near the blade surface and the flow from the pressure side to suction side interfere with each other which induced the loss region.

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  • Fluid exciting force due to flutter and rotor-stator interactions in axial flow turbines

    K. Ajiro, K. Matsuda, K. Onishi, T. Mineshima, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 2 )  2019.03

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    In recent years, the size and the speed of axial flow type hydraulic turbines have been continuously increased, leading to an increase of the fluid exciting forces due to rotor-stator interactions in hydraulic machines featuring both rotor and stator. In addition, the use of composite material for the blades of large hydraulic machines is increasingly investigated. Such flexible and lightweight hydrofoils can however easily experience self-excited vibration such as flutter effect. Fluid exciting forces generated in hydraulic machines might cause resonance, fatigue of the blade and finally damage. This paper aims to evaluate fluid exciting forces produced by rotor-stator interactions in axial flow turbines and the hydro-elastic response to the flutter of a flexible hydrofoil. To evaluate fluid exciting forces due to rotor-stator interactions, experiments are carried out using a closed-loop water channel featuring an axial flow turbine. The pressure distribution on the blade surface and the influence of axial distance between rotor and stator on the pressure fluctuations amplitude on the blade surface are investigated. A good agreement between experimental and numerical values is found. Regarding the flutter effect, FSI (Fluid Structure Interaction) simulation of one hydrofoil coupling RANS (Reynolds-averaged Navier-Stokes equations) and FEM (Finite Element Method) simulation is carried out to study the three-dimensional behaviour of the flutter.

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  • Design optimization of medium specific speed Francis turbines with unshrouded runners

    W. Takahashi, M. Shinji, Z. H. Liu, K. Miyagawa, Y. Hayashi

    IOP Conference Series: Earth and Environmental Science   240 ( 2 )  2019.03

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    In present, many undeveloped locations of small hydropower generation exist in Japan. To promote the use of small hydropower generation it is required to reduce costs and increase efficiency. Unshrouded runners are proposed to simplify the manufacturing process and also to reduce the manufacturing costs. In this paper, the computation results of optimized unshrouded runners are presented. This research was conducted to minimize the shroud tip leakage loss, which is the main loss of unshrouded runners. In the author's laboratory, medium specific speed (160 [m-kW]) Francis turbines was developed. For this 160 [m-kW] Francis turbines, investigation of internal flow and loss mechanism were done by computation. Using this loss mechanism which was revealed by rothalpy, the design of the same specific speed Francis turbines with unshrouded runners was optimized. For the new runners, shroud tip clearance and the pressure distribution of vane surfaces was changed. Due to this, shroud tip leakage flow has weakened. In the simulation of whole domain, 2.45% of improvement was confirmed on the design point.

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  • Statistical analysis of cavitation erosion impacts in a vibratory apparatus with copulas

    G. Taillon, K. Onishi, T. Mineshima, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 6 )  2019.03

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    A method of analysis of cavitation peaks (impact events) using copulas is developed. Impact events, otherwise known as peaks, are defined as maximum in the pressure amplitude applied to a material surface. These impact events were measured using a high speed pressure sensor in a cavitation apparatus based on the ASTM G32 standard. A total of 46180 impacts were measured over 100 realizations of 4ms long recording. First, the impact duration and amplitude's joint marginals are modeled as gamma distribution (part of the exponential family), determined by a Kolmogorov-Smirnov test (KS test). Then, copulas enable the study of the dependence structure of the measured impacts characteristics. The measured parameters are shown to not be independent but instead have a complex, asymmetric dependence structure. There are almost no impacts that have a combination of a high amplitude (>12MPa) and low duration (<5μs). The Tawn copula best fitted the data, as determined by a maximum likelihood method. An extension of the KS test to two dimensions demonstrated that the copula is a better fit compared with a joint distribution of independent marginals.

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  • Cavitation erosion resistance of high-strength fiber reinforced composite material

    G. Taillon, S. Saito, K. Miyagawa, C. Kawakita

    IOP Conference Series: Earth and Environmental Science   240 ( 6 )  2019.03

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    Cavitation erosion tests were performed using a cavitating jet apparatus inspired by the ASTM G134 standard on a high-strength fiber reinforced composite material named Vectran. These tests were also performed on metallic materials, namely Al, SUS304 stainless steel and AlBC, to determine the effect of their elastic modulus and acoustic impedance on the erosion. The effects of the jet parameters, the standoff distance and cavitation number were also observed. Using a high speed-pressure sensor, a measure of accumulated impact energy was made: the number of high amplitude force counts decreased with the standoff distance, while the optimal erosion distance was negatively proportional to the cavitation number. The higher the intensity, the higher was the maximal mean depth of erosion rate (MDER) for all materials. The erosion rate decreased with the young modulus, but it was observed to be linearly dependent on the material's acoustic impedance.

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  • Design optimization of a low specific speed centrifugal pump with an unshrouded impeller for cryogenic liquid flow

    T. Hayashi, Y. Nakamura, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 3 )  2019.03

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    Rocket engines require centrifugal pu mps used in its propellant feeding system to be smaller and lighter to increase the final speed of payloads, and be produced with lo wer costs. Reducing the number of stages and removing shroud rotating wall make pu mps lighter and easier to manufacture. Therefore, these pumps should be designed with higher head to reduce the number o f stages and have an unshrouded impeller. In this study, various shapes of shrouded and unshrouded impellers with the same meridional plane, that have various blade angle distributions, and splitter b lade shapes, have been analysed by a co mputational flu id dynamics(CFD) approach. Based on this survey, the impeller blade shape which demonstrates the highest head and efficiency has been designed considering the internal flow of the pump. As a result, it was observed that unshrouded impellers had the loss generation structure due to tip leakage flow wh ich was different fro m shrouded impellers had. Based on the above, a design method considering the tip leakage flow of unshrouded impeller was suggested.

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  • Development of high-efficiency and low-cost unshrouded turbine runner for small scale hydropower plant

    T. Aida, Y. Nakamura, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 2 )  2019.03

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    Facing a growing demand for low initial cost and high-efficiency small scale hydropower plants, a new type of Francis turbine was developed for Kazunogawa small hydropower plant with cooperation from industrial, governmental, and academic sectors. To reduce the cost of the turbine while increasing its efficiency, a prototype turbine with an unshrouded runner and a cylindrical casing was developed. The unshrouded runner was designed by Waseda University. Typically, the turbine runner for small scale hydropower is manufactured via a casting method; however, the unshrouded runner can be milled with a 5 axis CNC machine, thereby reducing cost and manufacturing lead time. A cylindrical casing has advantages of low fabrication cost and compact footprint. However, it had lower efficiency compared to a spiral casing with conventional design. Therefore, in this study, topology optimization based on CFD analysis was conducted on the casing and double circular cascade to improve efficiency. In addition, the axial thrust was estimated from CFD analysis to design the bearings and to determine the runner gap. Finally, a performance test was conducted on-site and peak efficiency of 91% was confirmed. This paper also reports the follow-up observation of the prototype turbine after commercial operation started.

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  • Unsteady RANS simulation of three-stage centrifugal pumps with different impeller-diffuser gaps

    T. Takamine, S. Watanebe, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 9 )  2019.03

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    In this study, unsteady RANS simulation is attempted for a three-stage centrifugal pump, a target pump for the workshop "Single- & Multi-Stage Pump Flow Prediction" which is being held in 29th IAHR Symposium on Hydraulic Machinery and Systems. A commercial code SCRYU/Tetra developed by Software Cradle Co. Ltd. is adopted for the unsteady RANS simulation. Our primary interest is to understand the effect of the gap between impeller trailing edge and diffuser leading edge on the axial thrust characteristics of the multi-stage centrifugal pumps. To do so, in addition to the simulation for the original pump model, the impeller-diameter cut model is also simulated. The diffuser inlet to the impeller outlet diameter ratio is 1.05 for the cut model against 1.02 for the original model. The good agreement is obtained for the hydraulic performance of the original model at the design flow rate, but only the fair agreement is obtained for the axial thrust force. From the pressure distributions inside the front and back side gap of the impeller, it is found that the discrepancy is due to that of the pressure distribution inside the back side gap of the second (and also perhaps the first) impeller. The effect of impeller-diffuser gap on the hydraulic performance and axial thrust force is predicted to be small at the design flow rate through the present computations. At the low flow rate, the balancing flow rate is significantly over-predicted by the present simulation. The reason for this remains unclear and will be hopefully made clear in our future study.

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  • Flow field and cavitation characteristics of hydrofoils coated with hydrophilic and hydrophobic polymers

    T. Mineshima, K. Onishi, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 6 )  2019.03

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    Tidal power turbines take advantage of tidal energy to generate renewable hydropower. Since the tidal turbines are fixed in the ocean, it is common to paint the blade and the structure of tidal energy generator with antifouling coating to prevent marine organisms from attaching to them. In this research, hydrophilic and hydrophobic coatings which are thought to be useful as countermeasures to prevent marine organisms' adhesion are studied. We focused on the influence of the (hydrophilic and hydrophobic) coatings on the cavitation and flow field characteristics. The hydrophilic coated foil restrained the cavitation inception and growth compared to the hydrophobic coated foil from our experiment. And then, FFT was carried out on the pressure fluctuation measured in each coating foil, and the absolute value of the pressure fluctuation amount and the difference in the fluctuation period were clarified. And as another characteristic of the coated foils, the flow field near the coating surface was investigated. The velocity distribution near the foil's surface was measured using Laser Doppler Velocimetry (LDV). In this experiment, a flat plate with or without the hydrophilic and hydrophobic coatings were used. As a result, differences in the boundary layer thickness and the velocity near the wall were revealed.

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  • Foreword

    Chisachi Kato, Kazuyoshi Miyagawa

    IOP Conference Series: Earth and Environmental Science   240 ( 1 )  2019.03

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  • DYNAMIC CHARACTERISTICS OF UNSHROUDED IMPELLERS EQUIPPED WITH BALANCE PISTON SYSTEMS FOR ROCKET TURBO PUMPS

    Tomoyuki Hayashi, Mamiko Yoshimura, Keisuke Matsumoto, Kazuyoshi Miyagawa, Satoshi Kawasaki, Junya Takida, Hiromichi Hiraki, Naohito Suwa

    PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2019, VOL 3B   3B-2019  2019

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    Turbo pumpsfor rocket engines often equipped balance piston (BP) systems at the back-shroud of the impellers for cancelling their axial thrust. The BP system is self-balancing and stable under quasi-static conditions, but it is known that the BP systems can be unstable under certain dynamic conditions. The performance characteristics of turbo pumps equipped with unshrouded impellers might be affected by the axial position of the rotor. Thus it is necessary to consider this effect when calculating the balance of axial thrust. Few experiments have determined the characteristics of unshrouded impellers equipped with BP systems yet.In this research, an experimental study of a model turbo pump for rocket engines was carried out. This pump had an unshrouded impeller a BP system, a vaned diffuser, and a volute. Axial forced oscillations were applied on the rotor of the pump by an active magnetic bearing (AMB) test facility. This setup can oscillate with freely-selected amplitude and frequency applying thrust to the rotor. During the oscillations, the fluctuation of axial thrust under the operating conditions was monitored using strain gauges. The axial thrust compensation ability and the response of the BP system were evaluated by analyzing the magnitude, amplitude and phase delay of the axial position of the rotor. Moreover, 3D simulations and ID simulations were carried out for the model pump. In the 3D simulations, computational fluid dynamics (CFD) was used to calculate the internal flow of the model pumps. The BP system was equipped with an impeller on which were applied forced oscillations. The impeller movement was modeled using a mesh morphing method. The 1D simulation predicted the axial thrust by calculating the mass flow balance using the geometry of the model pump.The phase lag between the axial position and the thrust was dominated by the pressure fluctuation at the BP chamber caused by the mass flow balance. The 3D simulations well predicted the fluctuation, but the characteristics of the BP system estimated by the 3D simulations were more stable than those determined by the experiments. On the other hand, the characteristics estimated by the ID simulation was less stable than those by the experiments. However, these simulations grasped the tendency of the BP system to become unstable as the oscillation frequency increases, and are effective in predicting the characteristics.

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  • UNSTEADY FLOW IN THE VANED DIFFUSER OF A LOW SPECIFIC SPEED CENTRIFUGAL PUMP WITH AN UNSHROUDED IMPELLER

    Asuma Ichinose, Tomoki Takeda, Kazuyoshi Miyagawa, Yohei Ogawa, Hideyo Negishi, Kazuki Niiyama

    PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2019, VOL 3B   3B-2019  2019

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    The unsteady internal flow in a low specific speed centrifugal pump was experimentally and numerically investigated. Unshrouded impellers enable high head designs but on the other hand, they exhibit complicated internal flow and an efficiency decline compared to shrouded impellers. Furthermore, the complicated impeller outlet flow induces unsteady internal flow in the vaned diffuser. Therefore, a detailed investigation of the internal flow is required in order to increase the efficiency of these low specific speed centrifugal pumps. The aims of this paper are to clarify the loss mechanisms in the impeller and to investigate the effect of impeller outlet flow to the diffuser internal flow at the design point. The detailed pump internal flow is investigated using unsteady computation, which enables the computation of the 3D flow pattern. The reversed flow and the secondary flow are induced by the tip leakage flow, and this creates a high loss region in the blade-to-blade region. On the other hand, the mixing effect is remarkable at the impeller outlet, and this affects the creation of the wake. This flow behavior makes the internal flow of the diffuser unsteady and the diffuser performance fluctuates due to the impeller wake at the design point.

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  • Unsteady behavior of a radial fan in a pulsating flow field

    Saki Shiratori, Yohei Nakamura, Kensuke Yasui, Sho Yamada, Kazuyoshi Miyagawa

    Open Archives of the 16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016    2019

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    The unsteady behavior of a radial fan in a pulsating flow field was studied experimentally. In a pulsating flow, compressor and turbine operating points do not match their steady performance curve, but exhibit a hysteresis loop instead. The shape of the hysteresis loop depends on the pulsating frequency. Measurements to calculate the Bode diagram of the fan and the phase lag of pressure and flow rate indicate that the phase lag controls the hysteresis loop. Moreover, to clarify the influence of air column resonance, the diffuser pump test was performed as a basic study. Computational fluid dynamics (CFD) analysis of the radial fan was carried out, and its results were compared with the experiment results. The unsteady curve calculated by CFD formed a hysteresis loop as observed in the experiment results.

  • Internal flow and stability of balance piston for a rocket pump

    Norio Kimura, Yuki Yoshii, Kengo Uchiyama, Kazuyoshi Miyagawa

    Open Archives of the 16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016    2019

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    In centrifugal pumps, axial thrust balancing is an important factor for stable operation. In particular, in rocket pumps, the stability of rotor assembly is very important to realize reliable high-pressure fluid delivery. Although balance piston, which is one of the self-compensating axial thrust balancing systems, was often used, there are sometimes axial vibration problems on the rotor. In this study, we examine static and dynamic characteristics of balance piston by performing experiments, computational fluid dynamics (CFD), and one-dimensional (1D) simulations, and we calculate parameters such as the static pressure in balance piston chamber and flowrate, orifice flow coefficient, phase difference from the rotor axial displacement to the static pressure fluctuation in the balance piston chamber. The results confirm that the experimental results can be predicted to some degree by performing simulations. Especially, it is found that the CFD simulation can be used to effectively predict the stability of balance piston..

  • Counter-rotating type tidal stream power unit: Excellent performance verified at offshore test

    Isao Samura, Kazuo Kuwano, Ryunosuke Kawashima, Taizo Oda, Takumi Imakyurei, Hideyuki Inoue, Yuuichiro Tokunaga, Toshiaki Kanemoto, Kazuyoshi Miyagawa, Toshihiko Miwa, Hiroshi Yamanokuchi

    29TH IAHR SYMPOSIUM ON HYDRAULIC MACHINERY AND SYSTEMS   240 ( 5 )  2019

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    A counter-rotating type tidal stream power unit, composed of tandem propellers and a peculiar generator with double rotatable armatures, was provided for verification tests at offshore. The front propeller with diameter of 1 m has three blades, and the rear propeller with diameter of 0.95 m has five blades. The blade profiles were optimized with the blade element-momentum theory and CFD, and then covered with CFRP. The front and the rear propellers connect to inner and outer armatures in a synchronous type generator with net output 1.5 kW, whose efficiency was improved by heat pipes and the modification of the armature profiles. The shafts are equipped with mechanical seals to protect electric circuits from seawater. A rotational speed control system was also prepared not only to adjust the output but also to overcome the static friction torque due to bearings, slip rings and mechanical seals while starting-up. The power unit takes the maximum output with excellent efficiency at the relative tip speed ratio specified in the unit design. The unit can start-up after maintenance works and the output can be adjusted smoothly in the stream.

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  • Influence of guide vane clearance on internal flow of medium-specific speed Francis turbine

    Gnanasekaran KishorKumar, Tadachika Tanaka, Naoki Yamaguchi, Toui Taniwaki, Kazuyoshi Miyagawa, Wataru Takahashi

    29TH IAHR SYMPOSIUM ON HYDRAULIC MACHINERY AND SYSTEMS   240 ( 2 )  2019

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    In Francis hydro turbines, a small clearance between the guide vane blade and the facing plate is crucial in pivoting the guide vane blade and controlling the flow rate of the turbine. This clearance-to-blade height ratio is inversely proportional to the scale of the hydro turbine. Smaller hydro turbines have higher clearance-to-blade height ratio than larger ones. Most of the time, this clearance is not included in the simulation model for it can cause inconsistencies between the computation and model turbine. This paper is focused on the various guide vane clearance and its influences on the flow. Firstly, steady numerical calculation of the turbine model (casing, stay vanes, guide vanes and draft) with and without guide vane reference clearance was carried out using the commercial code ANSYS CFX. Experiments were conducted on model turbine of specific speed 180 [m-kW] with guide vane reference clearance. The inter-blade pressure near the leading edge (LE), mid-chord and the trailing edge (TE) of the guide vane were obtained using the pressure sensor located along the circumference of the turbine casing. The result shows a good agreement between numerical computation and experiment. Furthermore, guide vane models with different clearance heights were simulated and the impact on runner inlet energy loss was investigated. In conclusion, it can be clarified that the roll-up flow from the guide vane clearance interacted with the main flow upstream of the runner which then caused loss to the turbine performance.

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  • Influence of clearance flow on disk friction loss in low specific speed hydraulic machines

    Ryutaro Ujiie, Asuma Ichinose, Yohei Nakamura, Kazuyoshi Miyagawa, Takeshi Sano

    29TH IAHR SYMPOSIUM ON HYDRAULIC MACHINERY AND SYSTEMS   240 ( 3 )  2019

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    Generally, in industrial applications, multi-stage pumps are used to obtain high working pressure. However, utilizing these pumps requires larger body size and longer shafts which will lead to substantial costs. As a result, a low specific speed machine is needed to minimize costs. In such case, energy can be saved and manufacturing costs can be reduced by increasing the efficiency of these low specific speed machines disk friction loss is one important cause of friction in low specific speed machines. It is caused by fluid friction occurring in the clearances between the shroud and back-shroud of the impeller and the casing. This loss is not directly related to the energy conversion in turbo machines, however it is related to the main characteristics of a machine. It will be increased proportionally with the impeller diameter and decreased with its specific speed. In this research, a test apparatus for measuring friction torque on a rotating disk was established, including a pressure resistant tank and boost pump connected in a closed loop using water as the working fluid. The sample rotating disk simulated the leakage flow path between the back-shroud and the casing of a centrifugal pump. Disks with different clearances were prepared, and fluctuations of torque were studied as a function of flow rate and Reynolds number. As a result, an optimum value for disk clearance with the minimum torque was observed to exist under each flow condition. CFD analysis was performed using a model simulating the disk clearance to understand the internal flow structure. For purpose of validation, the radial distribution of static pressure on the stationary wall was simulated by CFD and compared to experimental results. The CFD analysis agreed with the experimental distribution of wall static pressure in an acceptable manner, therefore it is proved that CFD model can reliably be used in evaluation of disk friction loss. Moreover, disk friction loss variation as a function of flow rate was investigated with inward and outward flow directions. It is seen that for both directions, disk friction loss decreases with flow rate. However, a vortex structure was observed at the inlet of the disk clearance for inward flow direction. Size of the vortex structure changes as a function of flow rate and has an influence on disk friction loss. The occurrence of this vortex structure may increase the efficiency of actual low specific speed machinery.

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  • Internal flow and loss mechanisms of specific speed 160 m-kW shroudless hydro turbine

    Z. H. Liu, M. Shinji, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   163 ( 1 )  2018.07

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    High efficiency and low-cost hydro turbines are becoming more popular for medium and small-scale hydropower generation in underdeveloped locations. Because of this, a shroudless hydro turbine of medium specific speed 160 [m-kW] was developed based on a low specific speed 80 [m-kW] design concept previously studied in the author's laboratory. We are aiming to develop an optimal design method and further improve performances of the medium- specific speed 160 [m-kW] shroudless hydro turbine. The most important factors are the internal flow and the loss mechanism of each flow path component. In this study, the internal flow and loss mechanisms were investigated and clarified by experimental and computational approaches. The main loss mechanisms in the double circular cascade is the high swirling strength vortices extending from the guide vane inlet to the outlet near the end wall of guide vanes. Furthermore, it has been found that the interference of the secondary flow and leakage flow, and the tip leakage vortex are the predominant loss mechanisms of the shroudless runner.

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  • INVESTIGATION OF INTERACTION BETWEEN TIP LEAKAGE FLOW GENERATED BY UNSHROUDED IMPELLER AND DIFFUSER INTERNAL FLOW

    Asuma Ichinose, Norio Kimura, Mamiko Yoshimura, Tomoyuki Hayashi, Kazuyoshi Miyagawa

    PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER MEETING, 2018, VOL 3    2018

     View Summary

    Rocket turbo pumps and industrial pumps such as water feed pumps are required to work under high pressure conditions, therefore low specific speed pumps are needed in spite of high rotational speed. In recent years, unshrouded impellers were used because of easy manufacturing and cost reduction. However, when low specific speed unshrouded impellers are used in such conditions, complex tip leakage flow occur and decrease impeller performance. In addition, splitter blades are often used, the internal flow becomes even more complicated. Therefore, such the internal flow of the unshrouded impeller must be clarified. In this research, we have studied such a centrifugal pump, and we have analyzed the internal flow using experiments and CFD (Computational Fluid Dynamics) simulations.The experimental verification was carried out by measuring the total pressure distribution on the outlet of the impeller and the diffuser. The unsteady static pressure distribution at the shroud side of the impeller was measured to confirm pump performance. We used two types of CFD simulation to evaluate the internal flow in detail. In the first CFD simulation, the unsteady internal flow of an impeller was evaluated by carrying out DES (Detached Eddy Simulation) with a periodic boundary condition that does not contain the diffuser. In the second CFD simulation, interaction between the impeller leakage flow and the diffuser internal flow was evaluated by DES with the whole impeller and diffuser.From the experimental verification and CFD simulation, it was confirmed that a large-scale vortex structure caused by the tip leakage flow and the secondary flow was observed in the impeller blade-to-blade. And the influence of the impeller leakage flow on the diffuser internal flow and the diffuser performance was evaluated.From the above studies, it was confirmed that the tip leakage flow has a large influence on the impeller internal flow and the diffuser performance.

  • CLOGGING MECHANISMS OF VORTEX PUMPS : FIBROUS MATERIAL MOTION CAPTURE AND SIMULATION WITH A CFD AND DEM COUPLING METHOD

    Yamato Imasaka, Hitoshi Kanno, Sumio Saito, Kazuyoshi Miyagawa, Motohiko Nohmi, Miho Isono, Masahito Kawai

    PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER MEETING, 2018, VOL 3    2018

     View Summary

    Since wastewater pumps used in sewage systems have a trade-off relationship between non-clogging ability and efficiency, many internal flow and performance estimation studies so far have focused on optimizing both parameters. Here we focus on vortex pumps with a large space that allows foreign matters to pass through inside the casing that are used as sewage pumps.In this paper, using experimental and numerical methods, we clarified clogging mechanism in the pumps using CFD (Computational Fluid Dynamics), Motion Capture and PIV (Particle Image Velocimetry) method.Firstly, since it was difficult to observe the motion of foreign matter in the pumps, a simple experimental apparatus was built to quantify it. Five cylindrical rods were set in a rectangular water passage made of acrylic that has an 80mm*80mm cross section. The motion of strings in the passage was studied with experiments and computations. Strings were chosen as foreign matter because they are comparatively easy to compute and experiment with compared to fabric for example. In the experiments, the motion of strings could be recorded with a high-speed video camera and their motions were quantified with two-dimensional motion capture system.In the computations, the motion of strings was simulated using DEM (Discrete Element Method) in the CFD software STAR-CCM+ by connecting particles with straight lines and coupling CFD with DEM. It is a numerical value method in which the motion and interaction of a large number of disintegrating objects is simulated. Its characteristic is that the point of contact between the particles is included in the equation of motion. Particles are connected by massless rods. These rods transmit force and momentum to each particle. Furthermore, the force between each particle is computed of the interaction between soft-particles and their bonding strength. In order to formulate the contact force between the particles, the springdashpot system is used. In addition, the optimal parameters of the DEM particles were obtained by conducting a parameter study.We confirmed that the motion of the strings in the flow direction coincided with at a high precision in the passage. Furthermore, by applying the computational method with the above results, we were able to simulate the motion of strings in a vortex pump. We found that strings were pulled back into the pump by the backflow in the tongue of the pump. This backflow was observed using PIV results, providing experimental confirmation of this mechanism. Moreover, we were able to simulate the motions of fibrous materials in the passage and vortex pump.

  • INFLUENCE OF PULSATING FLOW ON TURBINE PERFORMANCE INVESTIGATED BY DES AND PIV

    Yohei Nakamura, Manato Chinen, Masamichi Sakakibara, Kazuyoshi Miyagawa

    PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER MEETING, 2018, VOL 3    2018

     View Summary

    Recently, the downsizing of engine using turbocharger attracts more and more attention. Generally speaking, a turbocharger is usually designed based on its steady performance curve. However, the operating point of a turbocharger turbine does not match the steady operating point: instead it shows hysteresis behavior because of the pulsating flow generated by the engine valves. Unfortunately, turbine efficiency drops under pulsating flow conditions, but the loss mechanisms of the turbine under these conditions are not understood. Internal flow measurements under pulsating flow are actually very difficult. In this study, the internal flow under pulsating conditions was measured using a high speed PIV (Particle Image Velocimetry) system. The loss mechanisms were investigated by experimental investigation and computational fluid dynamics (CFD). The instantaneous pressure, velocity and torque were measured using a turbine experimental apparatus at WASEDA University. To generate the pulsating flow, a pulse generator was placed upstream of the turbine: a rotational disk with holes that only lets the flow through periodically. The pulsating frequency could be changed freely by changing the, rotational speed of the disk. The visualization using PIV was performed at a frequency of 1 kHz at the turbine outlet.Many fine vortices which rotate in various directions were observed under pulsating flow. Such vortices mix in the exhaust diffuser and under low frequency flow, mixing of vortices took a long time. It was observed that one loss mechanism under unsteady conditions is the mixing of vortices at the turbine outlet.CFD was performed using ANSYS-CFX, with approximately 10 million nodes. Turbulent flows were treated by using the Reynolds-averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) with the SST k-a) turbulence model.It was confirmed that the wheel and exhaust diffuser total pressure loss under pulsating flow was higher under steady flow conditions. In addition, the total pressure loss is proportional to the flow pulsation frequency. The analysis with DES agreed with the PIV results qualitatively. On the other hand, the analysis with RANS could not simulate the flow pattern at the turbine outlet.

  • Clogging mechanisms of vortex pumps: Fibrous material motion capture and simulation with a CFD and DEM coupling method

    Yamato Imasaka, Kazuyoshi Miyagawa, Hitoshi Kanno, Motohiko Nohmi, Sumio Saito, Miho Isono, Masahito Kawai

    American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM   3  2018

     View Summary

    Since wastewater pumps used in sewage systems have a trade-off relationship between non-clogging ability and efficiency, many internal flow and performance estimation studies so far have focused on optimizing both parameters. Here we focus on vortex pumps with a large space that allows foreign matters to pass through inside the casing that are used as sewage pumps. In this paper, using experimental and numerical methods, we clarified clogging mechanism in the pumps using CFD (Computational Fluid Dynamics), Motion Capture and PIV (Particle Image Velocimetry) method. Firstly, since it was difficult to observe the motion of foreign matter in the pumps, a simple experimental apparatus was built to quantify it. Five cylindrical rods were set in a rectangular water passage made of acrylic that has an 80mm*80mm cross section. The motion of strings in the passage was studied with experiments and computations. Strings were chosen as foreign matter because they are comparatively easy to compute and experiment with compared to fabric for example. In the experiments, the motion of strings could be recorded with a high-speed video camera and their motions were quantified with two-dimensional motion capture system. In the computations, the motion of strings was simulated using DEM (Discrete Element Method) in the CFD software STAR-CCM+ by connecting particles with straight lines and coupling CFD with DEM. It is a numerical value method in which the motion and interaction of a large number of disintegrating objects is simulated. Its characteristic is that the point of contact between the particles is included in the equation of motion. Particles are connected by massless rods. These rods transmit force and momentum to each particle. Furthermore, the force between each particle is computed of the interaction between soft-particles and their bonding strength. In order to formulate the contact force between the particles, the spring-dashpot system is used. In addition, the optimal parameters of the DEM particles were obtained by conducting a parameter study. We confirmed that the motion of the strings in the flow direction coincided with at a high precision in the passage. Furthermore, by applying the computational method with the above results, we were able to simulate the motion of strings in a vortex pump. We found that strings were pulled back into the pump by the backflow in the tongue of the pump. This backflow was observed using PIV results, providing experimental confirmation of this mechanism. Moreover, we were able to simulate the motions of fibrous materials in the passage and vortex pump.

    DOI

  • Experimental analysis of diffuser rotating stall in a three-stage centrifugal pump

    Taiki Takamine, Daichi Furukawa, Satoshi Watanabe, Hiroyoshi Watanabe, Kazuyoshi Miyagawa

    International Journal of Fluid Machinery and Systems   11 ( 1 ) 77 - 84  2018

     View Summary

    Rotating stall phenomenon limits the operation range of turbomacnines, therefore it is important to understand the crucial parameters of this phenomenon. In the present study, the diffuser rotating stall in a three-stage centrifugal pump was experimentally studied. Examined main parameter was an axial offset of rotor against the stationary part, which might be unavoidable due to accumulation of geometrical tolerances and assembling errors. The effect of leakage flow rate at the balance drum section employed as a thrust balancing device, which increases the thru-flow rate at the first and second stages diffusers. was also studied. The effect of rotor axial offset was clearly observed and, with the rotor axial offset to the suction side, the rotating stall appeared only at the third stage diffuser. By setting the balance flow rate set to zero, the onset range of rotating stall became wider m the first and second stage diffusers, which was well explained by the decrease of the thru-flow rate.

    DOI

  • Investigation of interaction between tip leakage flow generated by unshrouded impeller and diffuser internal flow

    Asuma Ichinose, Norio Kimura Mamiko Yoshimura, Tomoyuki Hayashi, Kazuyoshi Miyagawa

    American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM   3  2018

     View Summary

    Rocket turbo pumps and industrial pumps such as water feed pumps are required to work under high pressure conditions, therefore low specific speed pumps are needed in spite of high rotational speed. In recent years, unshrouded impellers were used because of easy manufacturing and cost reduction. However, when low specific speed unshrouded impellers are used in such conditions, complex tip leakage flow occur and decrease impeller performance. In addition, splitter blades are often used, the internal flow becomes even more complicated. Therefore, such the internal flow of the unshrouded impeller must be clarified. In this research, we have studied such a centrifugal pump, and we have analyzed the internal flow using experiments and CFD (Computational Fluid Dynamics) simulations. The experimental verification was carried out by measuring the total pressure distribution on the outlet of the impeller and the diffuser. The unsteady static pressure distribution at the shroud side of the impeller was measured to confirm pump performance. We used two types of CFD simulation to evaluate the internal flow in detail. In the first CFD simulation, the unsteady internal flow of an impeller was evaluated by carrying out DES (Detached Eddy Simulation) with a periodic boundary condition that does not contain the diffuser. In the second CFD simulation, interaction between the impeller leakage flow and the diffuser internal flow was evaluated by DES with the whole impeller and diffuser. From the experimental verification and CFD simulation, it was confirmed that a large-scale vortex structure caused by the tip leakage flow and the secondary flow was observed in the impeller blade-to-blade. And the influence of the impeller leakage flow on the diffuser internal flow and the diffuser performance was evaluated. From the above studies, it was confirmed that the tip leakage flow has a large influence on the impeller internal flow and the diffuser performance.

    DOI

  • Influence of pulsating flow on turbine performance investigated by DES and PIV

    Yohei Nakamura, Manato Chinen, Masamichi Sakakibara, Kazuyoshi Miyagawa

    American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM   3  2018

     View Summary

    Recently, the downsizing of engine using turbocharger attracts more and more attention. Generally speaking, a turbocharger is usually designed based on its steady performance curve. However, the operating point of a turbocharger turbine does not match the steady operating point: instead it shows hysteresis behavior because of the pulsating flow generated by the engine valves. Unfortunately, turbine efficiency drops under pulsating flow conditions, but the loss mechanisms of the turbine under these conditions are not understood. Internal flow measurements under pulsating flow are actually very difficult. In this study, the internal flow under pulsating conditions was measured using a high speed PIV (Particle Image Velocimetry) system. The loss mechanisms were investigated by experimental investigation and computational fluid dynamics (CFD). The instantaneous pressure, velocity and torque were measured using a turbine experimental apparatus at WASEDA University. To generate the pulsating flow, a pulse generator was placed upstream of the turbine: a rotational disk with holes that only lets the flow through periodically. The pulsating frequency could be changed freely by changing the rotational speed of the disk. The visualization using PIV was performed at a frequency of 1 kHz at the turbine outlet. Many fine vortices which rotate in various directions were observed under pulsating flow. Such vortices mix in the exhaust diffuser and under low frequency flow, mixing of vortices took a long time. It was observed that one loss mechanism under unsteady conditions is the mixing of vortices at the turbine outlet. CFD was performed using ANSYS-CFX, with approximately 10 million nodes. Turbulent flows were treated by using the Reynolds-averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) with the SST k-ω turbulence model. It was confirmed that the wheel and exhaust diffuser total pressure loss under pulsating flow was higher under steady flow conditions. In addition, the total pressure loss is proportional to the flow pulsation frequency. The analysis with DES agreed with the PIV results qualitatively. On the other hand, the analysis with RANS could not simulate the flow pattern at the turbine outlet.

    DOI

  • Application of CFD analysis for static and dynamic characteristics of hydrodynamic journal bearing

    Kenichiro Takenaka, Tomoyuki Hayashi, Kazuyoshi Miyagawa

    Open Archives of the 17th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2017    2017

     View Summary

    Journal bearings are one of the most important mechanical elements for the stable operation of rotors. Rotational machinery is becoming larger and more complicated in recent years, so proper design of bearings is necessary to offer stable support. However, bearings with shapes and operating conditions that can not be predicted by the conventional Reynolds equation method exist. In this paper,therefore, a prediction method of vibration characteristics of journal bearings using CFD was constructed. To calculate the dynamic characteristics, mesh morphing methods simulating two oscillating states were studied. In order to compare with the calculation results, an active oscillating rotor using magnetic bearings was constructed. As a result, the calculation results were roughly consistent with the experimental results, and a prediction method by CFD was constructed.

  • Influence of hydrophilic and hydrophobic coating on hydrofoil performance

    Kaoruko Onishi, Kunimasa Matsuda, Kazuyoshi Miyagawa

    Open Archives of the 17th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2017    2017

     View Summary

    Tidal power turbines take advantage of tidal energy to generate renewable hydropower. Since the tidal turbines are fixed in the ocean, it is common to paint the blade and the structure of tidal energy generator with antifouling coating to prevent marine organisms from attaching to them. Therefore, it is important to predict the influence of the coatings on the tidal turbine’s performance. In this paper, hydrophilic and hydrophobic coatings which are known to be useful in antifouling were studied from the perspective of flow field and cavitation. Cavitation was visualized with a high-speed video camera and the cavitation characteristics of blades painted with hydrophilic or hydrophobic coatings were compared. With this visualization, it was possible to observe that the hydrophilic foil and hydrophobic foil had distinctive characteristics in cavitation inception and growth. Moreover, the reliability of both coatings was evaluated in order to discuss whether these coatings were useful for long. Immersion tests were carried out to evaluate the deterioration of the coatings in pure water. In addition, magnetostriction vibratory tests were carried out to evaluate the resistance to cavitation erosion of both coatings. From these investigations, a chemical transformation of the hydrophilic coating was observed. Moreover, both coatings were easily removed when they were exposed to strong cavitation impacts.

  • EXPERIMENTAL INVESTIGATION ON DIFFUSER ROTATING STALL IN A THREE-STAGE CENTRIFUGAL PUMP

    Taiki Takamine, Satoshi Watanabe, Daichi Furukawa, Hiroyoshi Watanabe, Kazuyoshi Miyagawa

    PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER MEETING, 2017, VOL 1A   1A-2017  2017  [Refereed]

     View Summary

    Rotating stall phenomenon frequently causes the troubles such as vibrations acting on the shaft system and reduces the reliability of turbomachines. In the present study, the diffuser rotating stall in a. three-stage centrifugal pump was experimentally studied. Special emphasises were placed on the geometrical conditions; an axial offset of rotor against the stationary part, which might be unavoidable due to accumulation of geometrical tolerances and assembling errors., and the radial clearances of annular leakage paths which increases the thru-flow rate at the impellers and the first and second stage diffusers. As a result, with the rotor axial offset to the suction side, the rotating stall appeared only at the third stage diffuser, while with that to the discharge side, the rotating stall was more significant. By enlarging the leakage flow passages at the inter-stage bush and the balancing flow channel, the onset range of rotating stall became narrower in the first and second stage diffusers, which was well explained by the increase of the thru-flow rate. On the other hand, with the enlarged leakage passage at the liner ring, the onset range became slightly wider.

    DOI

  • Study on flow instability in a diffuser with swirling flow under several conditions of pipe length and swirl intensity

    R. Matsuzaka, T. Nakashima, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   49 ( 8 )  2016.12

     View Summary

    A swirling flow in a diffuser such as a draft tube of a hydro turbine may induce the flow instabilities accompanied by pressure fluctuations known as vortex rope behaviour and cavitation surge. Cavitation surge is the self-excited oscillation, which induces the large flow rate fluctuation that results from the change of the cavity volume. In this research, the investigation of the effect of the pipe length and the swirl intensity on the flow instabilities in a diffuser was performed by experiments and numerical analyses using the draft tube component experimental facility. The length of the pipe was modified by up to about 25 times as long as the diameter of the throat in order to validate the one-dimensional analyses. In addition, the swirl intensity was changed by replacing another swirl generator. The frequency of cavitation surge was changed with regard to the swirl intensity as the one-dimensional analyses in the previous study has predicted it. Unsteady numerical simulations of the swirling flow with cavitation in the diffuser was performed. The results of experiments and numerical analyses correspond qualitatively with the result of the one-dimensional analyses, which suggested that the coupling with the experiments, CFD analyses and the one-dimensional analyses is the more effective way in order to predict the flow instabilities in the diffuser.

    DOI

  • Numerical simulation of cavitation surge and vortical flows in a diffuser with swirling flow

    Bin Ji, Jiong Wang, X. Luo, K. Miyagawa, L. Z. Xiao, X. Long, Yoshinobu Tsujimoto

    Journal of Mechanical Science and Technology   30 ( 6 ) 2507 - 2514  2016.06

     View Summary

    The strong swirling flow at the exit of the runner of a Francis turbine at part load causes flow instabilities and cavitation surges in the draft tube, deteriorating the performance of the hydraulic power system. The unsteady cavitating turbulent flow in the draft tube is simplified and modeled by a diffuser with swirling flow using the Scale-adaptive simulation method. Unsteady characteristics of the vortex rope structure and the underlying mechanisms for the interactions between the cavitation and the vortices are both revealed. The generation and evolution of the vortex rope structures are demonstrated with the help of the iso-surfaces of the vapor volume fraction and the Qcriterion. Analysis based on the vorticity transport equation suggests that the vortex dilatation term is much larger along the cavity interface in the diffuser inlet and modifies the vorticity field in regions with high density and pressure gradients. The present work is validated by comparing two types of cavitation surges observed experimentally in the literature with further interpretations based on simulations.

    DOI

  • Nonlinear Vibration Induced by the Water-film Whirl and Whip in a Sliding Bearing Rotor System

    Zhai Liming, Luo Yongyao, Wang Zhengwei, Kitauchi Seishiro, Miyagawa Kazuyoshi

    CHINESE JOURNAL OF MECHANICAL ENGINEERING   29 ( 2 ) 260 - 270  2016.03

     View Summary

    Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.

    DOI

  • Study of flow instability in off design operation of a multistage centrifugal pump

    Akiha Shibata, Hideto Hiramatsu, Shutaro Komaki, Kazuyoshi Miyagawa, Manabu Maeda, Shun Kamei, Ryota Hazama, Takeshi Sano, Masamichi Iino

    JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY   30 ( 2 ) 493 - 498  2016.02  [Refereed]

     View Summary

    In recent years, attempts have been made to make multistage centrifugal pumps smaller in size and more efficient. However, such designs are known to cause positive-slope phenomena in the Q-H curve, especially under low-flow conditions. These phenomena, which have thus far been studied experimentally and numerically, stem from flow instability in the pump. However, their mechanisms have not yet been clarified because it depends on various parameters. In this study, we focused on diffuser rotating stall, observed in positive Q-H characteristics. This study elucidates the mechanism of positive-slope generation through experimental results and two-dimensional numerical analysis.

    DOI

  • FLOW INSTABILITY IN OFF DESIGN CONDITION OF VANED AND VANELESS DIFFUSER CENTRIFUGAL PUMP

    Hideto Hiramatsu, Akiha Shibata, Shutaro Komaki, Kazuyoshi Miyagawa, Takeshi Sano

    PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2015, VOL 1A, SYMPOSIA, PT 2   1A  2016

     View Summary

    In this study, the performance and the internal flow of one stage model centrifugal pump with both vaned and vaneless diffuser were investigated. To measure the internal flow of the diffuser and the impeller easily, air was used in this pump test. As a result of measuring pressure fluctuation, the rotating stall was observed in the vaned and vaneless diffuser. We clarified the generating mechanism and characteristics of the rotating stall in the diffuser and the difference between the unsteady flow fields in both diffusers. In case of the vaned diffuser, the number of rotating stall cells were 4 in the diffuser and the cell propagation speed ratio was about 5 percent of the impeller rotating speed. On the other hand, in case of the vaneless diffuser, the cell number was 2, and the propagation speed ratio was about 10 percent of that. These phenomena in both diffuser pumps were simulated by unsteady 2D and 3D CFD computations. By using these computations, the vortex at the trailing edge of the diffuser vanes blocked the flow and induced separate flow at the leading edge resulted in the rotating stall. This research indicated that these vortices induced the total pressure loss increasing. Also, the rotating stall was found not only in the diffuser but also in the impeller by the flow simulation of the vaneless diffuser. And it was confirmed that the vortices at the impeller trailing edge and leading edge in the stall cells cause the total pressure loss.

    DOI

  • MEASUREMENTS OF AXIAL AND RADIAL THRUST FORCES WORKING ON A THREE-STAGES CENTRIFUGAL PUMP ROTOR

    Tetsuya Yamashita, Satoshi Watanabe, Yoshinori Hara, Hiroyoshi Watanabe, Kazuyoshi Miyagawa

    PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2015, VOL 1A, SYMPOSIA, PT 2   1A  2016

     View Summary

    In this study, radial and axial thrust forces working on the whole rotor in a three-stages centrifugal pump are measured in a wide range of flow rate. The forces are measured at two floating journal bearings and one floating ball bearing, which are supported by the individual load cells. The effects of the offset of rotor position in the axial direction on the thrust forces are investigated. It is found that the effect of the axial offset is significant for the axial thrust force in the low flow rate range, whereas it has little influence on the head and efficiency performances in the whole flow rate range.

    DOI

  • DEVELOPMENT OF SHROUDLESS FRANCIS TURBINE

    Yohei Nakamura, Ryosuke Shima, Hiroki Komatsu, Saki Shiratori, Kazuyoshi Miyagawa

    PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2015, VOL 1A, SYMPOSIA, PT 2   1A  2016

     View Summary

    In this study, new design concepts were structured by DOE based on internal flow evaluation by CFD to realize the efficiency improvement, reliability improvement and cost reduction of a medium or small capacity hydro turbine. As a part of new concepts, shroudless type and shroud liner type runner shape were adopted. In shroud liner type, shroud line of meridional plane shape inclines at 45 degrees to rotational axis. By adopting shroud less type, runner can be made not by casting but by cutting work. For medium or small hydroelectric power plant, cost reduction is strongly required in comparison with larger scale hydro one. By adopting shroud liner type, efficiency was improved because of mitigating secondary flow. In addition, to improve reliability, shroud partial band was bonded at inlet of runner. This plays a role to prevent runner blade from breaking by tip rubbing.By using high-speed video camera and CFD analysis, it was clarified that runner outlet cavitation is caused by jet which is leakage in the tip clearance region and that leakage flow of outlet is larger than leakage flow of inlet.Moreover, by using the three-hole Pitot tube, the runner outlet flow distribution was measured and the validity of the design point was verified. Finally, by measurement of pressure on the wall of the stationary parts such as the guide vane, it was clarified that the total pressure loss of guide vane increases in stream-wise direction in low mass flow rate.In this report, the development of the shroudless Francis turbine based on the loss mechanism and flow investigation was described.

    DOI

  • Study on cavitation influence for pump head in an axial flow pump

    K. Hosono, Y. Kajie, S. Saito, K. Miyagawa

    Journal of Physics: Conference Series   656 ( 1 )  2015.12

     View Summary

    The size of axial flow pumps used in drainage pump stations has recently decreased, and their rotation speeds have increased, causing an increase in the risk of cavitation. Therefore, to provide highly reliable pumps, it is important to understand the internal flow of pumps under cavitating conditions. In this study, high-speed camera measurements and computational fluid dynamics analysis were performed to understand the cavitation performance of an axial flow pump. The mechanism that causes the head to change as a result of cavitation under low net positive suction head values is shown to be the balance between the increasing angular momentum and the loss indicated by the changing streamlines.

    DOI

  • Development of high-efficiency and low-cost shroudless turbine for small hydropower generation plant

    Yohei Nakamura, Hiroki Komatsu, Saki Shiratori, Ryosuke Shima, Sumio Saito, Kazuyoshi Miyagawa

    ICOPE 2015 - International Conference on Power Engineering    2015

     View Summary

    Hydropower generation is now attracting attention because of the world's energy problems. With cooperation from the industrial, governmental, and academic sectors, a new type of Francis turbine runner was developed for the Kazunogawa small hydropower generation plant. To validate its performance, a model turbine test facility was built at Waseda University, and a performance test was performed. This experiment confirmed that the maximum hydraulic efficiency was about 88%, and the operational point of maximum efficiency agreed with the design point. Then, using a high-speed video camera, three-hole pitot tube, and computational fluid dynamics (CFD) with cavitation analysis, the loss generation mechanism of the turbine was clarified. In addition, a vibratory cavitation erosion test was carried out to select the material for a prototype runner. It was found that the volume loss of ALBC was lower than that of any other material. At the first stage of prototype turbine design, a design point that could generate the maximum output for a year was calculated using the flow duration curve at the installation location. Then, the loss in the casing and double circular cascade was improved using CFD. Performance and load rejection tests were performed before the prototype turbine operation. It was confirmed that the maximum efficiency was 91%, and the runaway speed was lower than the value predicted by the model turbine test.

  • Study on flow instability and countermeasure in a draft tube with swirling flow

    Takahiro Nakashima, Ryo Matsuzaka, Kazuyoshi Miyagawa, Koichi Yonezawa, Yoshinobu Tsujimoto

    International Journal of Fluid Machinery and Systems   8 ( 4 ) 230 - 239  2015  [Refereed]

     View Summary

    The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.

    DOI

  • Numerical investigation of three-dimensional cavitation evolution and excited pressure fluctuations around a twisted hydrofoil

    Bin Ji, Xianwu Luo, Yulin Wu, Kazuyoshi Miyagawa

    JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY   28 ( 7 ) 2659 - 2668  2014.07  [Refereed]

     View Summary

    Unsteady cavitating turbulent flow around a twisted hydrofoil was analyzed to illustrate the physical mechanism of the cavitygenerated pressure fluctuations. The numerical simulations of cavitating flow were based on the Partially-Averaged Navier-Stokes (PANS) method and a mass transfer cavitation model. The validity of PANS model has been evaluated and confirmed in cavitation simulations by present authors using three different cases, 2D hydrofoil (Ji et al. 2012 [37]), 3D hydrofoil (Ji et al. 2013 [31]) and marine propeller (Ji et al. 2012 [38]), which shows that the PANS model with f (k) = 0.2 and f (epsilon) = 1 can obtain more accurate estimates of unsteady cavitating flows with large-scale fluctuations at a reasonable cost. In present paper we intended to shed light on the physical process responsible for the pressure fluctuations excited by cavitation. The cavity volume was analyzed to illustrate the relationship between the cavitation evolution and the pressure fluctuations. The results show that the cavity volumetric acceleration curve tracks remarkably well with the main features of the time-dependent pressure fluctuations except for the high frequency component. Thus, the cavity volumetric acceleration is the main source of the excited pressure fluctuations by cavitation. It is noted that the cavitation induced pressure fluctuations are transmitted along the suction surface of the hydrofoil and are synchronized with those on the pressure surface at the midplane of the twisted hydrofoil. Further, the pressure fluctuations on the pressure surface decrease towards the center from both the leading and trailing edges of the hydrofoil, with a minimum at 60% chord length from the leading edge.

    DOI

  • Study on clogging mechanism of fibrous materials in a pump by experimental and computational approaches

    H. Kudo, T. Kawahara, H. Kanai, K. Miyagawa, S. Saito, M. Isono, M. Nohmi, H. Uchida, M. Kawai

    IOP Conference Series: Earth and Environmental Science   22  2014

     View Summary

    Clogging trouble in a sewage pump is a serious problem caused by foreign substances like strings, towels, and cloths. However, mechanism of pump clogging is significantly complicated and it is difficult to clarify factors affecting pump clogging. In this paper, the simplified air duct test and axial fan test are introduced and some parameter studies based on design of experiments (DOE) were conducted. From the DOE results, the sensitivity of each parameter to the clogging was predicted. As the parameters related to the clogging, length and rigidity of the strings, leading shape and lean angle of obstacles, flow velocity in a measuring section were selected. Behavior of string in the pump was also observed in the actual pump apparatus and was compared to that in the air duct. Computational simulation with simplified flow fields and MBD (Multi Body Dynamics) was developed and applied to predict behavior of a string in the pump. These experiments and computation are effective to detect and classify the clogging mechanism. These approaches aided to establish one of the evaluation methods on anti-clogging performance against fibrous materials.

    DOI

  • Study on flow instability and countermeasure in a draft tube with swirling flow

    T. Nakashima, R. Matsuzaka, K. Miyagawa, K. Yonezawa, Y. Tsujimoto

    IOP Conference Series: Earth and Environmental Science   22  2014

     View Summary

    The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.

    DOI

  • An experimental study on pump clogging

    M. Isono, M. Nohmi, H. Uchida, M. Kawai, H. Kudo, T. Kawahara, K. Miyagawa, S. Saito

    IOP Conference Series: Earth and Environmental Science   22  2014

     View Summary

    For sewage pump that various foreign substance is flowed into, anti-clogging performance is a factor as important as pump efficiency in order to avoid clogging trouble by foreign substance. Many investigations about pump inner flow and pump efficiency estimation have been carried out conventionally in order to realize coexistence with anti-clogging performance and pump performance. And these results have been reflected in construction of the running water section design method. As a index of anti-clogging performance, "impeller passage diameter" which is diameter of spherical solid that can pass through the pump is used widely. And there are various type of the sewage pump which have large impeller passage diameter. However real cause of clog is not a solid, and it is fibrous material such as towel and clothes, vinyl and paper diaper. In most case these material accumulate in the pump, so that clog is occurred. In this study, for the purpose of quantification of anti-clogging performance against fibrous materials, the factor that affect to clogging of pump was investigated by pump model test using a string. The test is done based on Taguchi method. In this test, type of the pump model, diameter of the string, material of the string, length of the string and flow rate are selected for the factor, and the effect that they have on the clogging of the pump was investigated. As a result of this test, it was made clear that length of the string has a strong influence on the clogging of the pump. And from the result of this test, evaluation method of anti-clogging performance of the pump against fibrous material by using string was considered. According to the result of above test based on Taguchi method, it was assumed that quantification of anti-clogging performance against fibrous materials is possible by flowing plural strings into the pump and calculating the probability of passing. Plurality sewage pumps of different types were evaluated based on this assumption. And It was confirmed that it is possible to compare anti clogging performance of the pump against fibrous materials quantitatively. And the specification of the string was selected according to the result of the test based on Taguchi method. By this method, one of the evaluation method on anti-clogging performance against fibrous materials was established.

    DOI

  • Study on the flow stability and dynamic characteristics of a water bearing

    Liming Zhai, Seishiro Kitauchi, Kazuyoshi Miyagawa, Zhengwei Wang

    IET Conference Publications   2014 ( CP658 )  2014

     View Summary

    The dynamic characteristics of the sliding bearing have great influences on the vibration and stability of the rotorbearing coupled system. This study focus on a water lubricated bearing which supports the vertical rotor in atest facility. This rotor system is designed with maximum rotational speed of 5000 rpm and used to study the influence of water bearing on the rotor dynamics. Based on the unsteady computational fluid dynamics, a 3D model for the water film in the bearing with 3 grooves was built. The pressure oscillation in the water film was discussed. The dynamic characteristics including damping, stiffness and added mass of the bearing were calculated considering both the rotational effect and squeeze effect. The influences of the rotating speed of the shaft and prewhirl speed at water film inlet on the dynamic performance were also investigated. The results show that the instability of the film force on the journal is induced by the high-frequency vortexes in the grooves on the pad. At each rotational speed, the film force on the journal first decreases and then increase as the frequency ratio, while it increases with the increase of the rotational speed at each frequency. The rotational speed has great effects on the dynamic characteristics of bearing. Increasing the rotational speed contributes to strengthen the stability of the rotor system. The prewhirl velocity at the inlet has little impact on the dynamic characteristics and stability of the bearing. This study demonstrates the mechanism of lubrication dynamic characteristics of the siding bearing and shows the bearing nonlinear characteristics with the rotational speed. Using the CFD method to solve the water flow field is effective to predict the dynamic characteristics and can provide boundary conditions for the rotor dynamic analysis in the future study.

    DOI

  • Improvement of partial load performance of francis turbine runner

    Naoki Yamaguchi, Tadachika Tanaka, Kazuyoshi Miyagawa

    IET Conference Publications   2014 ( CP658 )  2014

     View Summary

    Turbine operation range has had to be extended to meet economic requirements in recent years. Specifically, efficiency under partial flow conditions has been improved by the development of low loss runners. The most effective runner design achieves suitable flow distribution from the runner exit, because the loss mechanism in the partial flow is due to swirl loss in the draft tube. In this study, a new design concept for improving turbine efficiency under low flow rate conditions is established and confirmed by both computation and experiment. The performance predicted by the CFD is compared with the experimental results and good agreement is observed. This report describes some runner shape improvement techniques to mitigate the effects of the flow conditions in a partial flow scenario, and validates their results through model performance testing.

    DOI

  • Numerical analysis of unsteady cavitation shedding dynamics around NACA66 hydrofoil by large-eddy simulation

    B. Ji, K. Miyagawa, X. W. Luo, Y. L. Wu, H. Y. Xu

    IOP Conference Series: Materials Science and Engineering   52 ( TOPIC 6 )  2013

     View Summary

    Large-Eddy simulation (LES) coupling with mass transfer cavitation model was used to resolve the turbulent flow structure with cavitation. The results will focus on the cavitation shedding dynamics around NACA66 hydrofoil. The predicted results compare well with the experimental measurements for steady/unsteady partial cavitating flows. Numerical visualizations of cloud cavity evolution and surface pressure signals show relatively good agreement with the experimental data. © Published under licence by IOP Publishing Ltd.

    DOI

  • Investigation of flow pattern downstream of spiral grooved runner cone in pump-turbine

    T. Sano, M. Maekawa, N. Okamoto, H. Yano, K. Miyagawa

    IOP Conference Series: Earth and Environmental Science   15 ( PART )  2012

     View Summary

    High amplitude of pressure fluctuation is observed in a draft tube of a hydraulic turbine and a pump-turbine, for the case of partial load operation. Several methods had been reported to mitigate the amplitude so far, such as, air or water injection to the draft tube, fins on the draft tube surface, or runner replacement with optimized velocity profile at runner exit. However, several problems for each method can be considered, such as, negative influence on efficiency, high cost, technical difficulties for installation, and so on. To solve these problems and satisfy the demand for mitigating the amplitude of pressure fluctuation simultaneously, a new runner cone with spiral grooves on the surface was developed. It was developed with unsteady draft tube calculation based on Design of Experiment (DOE) method, and the effect was confirmed by model tests. Finally, developed runner cone was installed to the prototype pump turbine, and predicted performance was confirmed by on-site tests. However, the reason why the grooved runner cone can mitigate the amplitude of pressure fluctuation in draft tube was not clarified. Therefore, numerical investigation focusing around runner cone was carried out. As a result, it was clarified that the velocity profile at runner outlet was modified by the grooved runner cone, such as, reverse flow downstream of runner cone and tangential velocity was reduced. It means the shear stress between main stream and dead water core region was weakened, therefore, it can be estimated that the amplitude of draft pressure fluctuation was reduced. © Published under licence by IOP Publishing Ltd.

    DOI

  • Cavitation surge in a small model test facility simulating a hydraulic power plant

    Koichi Yonezawa, Daisuke Konishi, Kazuyoshi Miyagawa, François Avellan, Peter Doerfler, Yoshinobu Tsujimoto

    International Journal of Fluid Machinery and Systems   5 ( 4 ) 152 - 160  2012

     View Summary

    Model tests and CFD were carried out to find out the cause of cavitation surge in hydraulic power plants. In experiments the cavitation surge was observed at flow rates higher and lower than the swirl free flow rate, both with and without a surge tank placed just upstream of the inlet volute. The surge frequency at smaller flow rate was much smaller than the swirl mode frequency caused by the whirl of vortex rope. An unsteady CFD was carried out with two boundary conditions: (1) the flow rate is fixed to be constant at the volute inlet, (2) the total pressure is kept constant at the volute inlet, corresponding to the experiments without/with the surge tank. The surge was observed with both boundary conditions at both higher and lower flow rates. Discussions as to the cause of the surge are made based on additional tests with an orifice at the diffuser exit, and with the diffuser replaced with a straight pipe.

    DOI

  • Status of Integrated IHX/Pump Development for JSFR

    Takuya Handa, Yasushi Oda, Yukihiko Ono, Kazuyoshi Miyagawa, Iwao Matsumoto, Kuniyuki Shimoji, Tomoyuki Inoue, Hiroyasu Ishikawa, Hiroki Hayafune

    JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY   48 ( 4 ) 669 - 676  2011.04

     View Summary

    This paper illuminates the status of research and development on the integrated IHX/Pump concept. The integrated IHX/Pump is the incorporated component of the intermediate heat exchanger (IHX) and the primary pump. Among the innovative technologies of the Japan Sodium-Cooled Fast Reactor (JSFR) in the Fast Reactor Cycle Technology Development (FaCT) project, the integrated IHX/Pump concept is one of the major innovative ideas for plant economy by reducing the amount of material in the primary cooling system and the building volume. This report summarizes the view of the integrated IHX/Pump, a development plan, evaluation methods, and the present test results with the 1/4-scale IHX/Pump test device.

    DOI

  • Effects of Inlet Velocity Distribution on Cavitation Surge in a Conical Diffuser

    YONEZAWA Koichi, KONISHI Daisuke, TANAKA Sayaka, MIYAGAWA Kazuyoshi, NICOLET Christophe, FARHAT Mohamed, AVELLAN Francois, TSUJIMOTO Yoshinobu

    Turbomachinery   39 ( 8 ) 458 - 466  2011

     View Summary

    By a theoretical study with an one-dimensional model and an experimental investigation with conical diffusers, it has been found that the diffuser effect of the draft tube cause cavitation surge. The present study focuses on effects of the swirl inflow and its velocity distribution at the inlet of the diffuser. Experimental and numerical investigations are carried out with a conical diffuser and a two-stage swirler at the inlet. Results show that the inlet circumferential velocity distribution affects the wall pressure distribution, and finally occurrence of the cavitation surge.

    DOI CiNii J-GLOBAL

  • A new methodology for suppressing pressure pulsation in a draft tube by grooved runner cone

    Takeshi Sano, Masayuki Ookawa, Hiromi Watanabe, Nobuaki Okamoto, Hiroshi Yano, Nobuhide Fukuda, Masatake Maekawa, Kazuyoshi Miyagawa

    ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011   1 ( D ) 1943 - 1950  2011

     View Summary

    High amplitude of pressure fluctuation is observed in a draft tube, for the case of partial load operation. Several methods had been reported to decrease the amplitude so far, such as, air or water injection to the draft tube, fins on the draft tube surface, or runner replacement with optimized velocity profile at runner exit. However, several problems for each method can be considered, such as, negative influence on efficiency, high cost, technical difficulties for installation, and so on. To solve these problems and satisfy the demand for decreasing the amplitude of pressure fluctuation simultaneously, a new runner cone with grooves on the surface was developed. As for the case with reversible pump turbine, grooved runner cone was developed with unsteady draft tube calculation based on Design of Experiment (DOE) method, and confirmed by model tests. Finally, developed runner cone was installed to the prototype pump turbine, and predicted performance was confirmed by on-site tests. Using this result, development of a new runner cone for hydraulic turbine had been started. For this case, meridian shape of the runner cone was also selected as a design parameter. Finally, we obtained the optimized shape, "diverged runner cone with spiral groove", and the performance is confirmed by the model test. In this paper, details of development, especially for the case of hydraulic turbine and considerations of the mechanism are treated. Copyright © 2011 by ASME.

    DOI

  • Technical Problems in Recent Turbomachinery Development

    MIYAGAWA Kazuyoshi

    Turbomachinery   38 ( 1 ) 4 - 11  2010

    CiNii J-GLOBAL

  • Experimental Study and Numerical Simulation of Cavity Oscillation in a Diffuser with Swirling Flow

    Changkun Chen, Christophe Nicolet, Koichi Yonezawa, Mohamed Farhat, Francois Avellan, Kazuyoshi Miyagawa, Yoshinobu Tsujimoto

    International Journal of Fluid Machinery and Systems   Vol.3 ( No.1 ) 80 - 90  2010.01

    DOI CiNii

  • Experimental Study and Numerical Simulation of Cavity Oscillation in a Conical Diffuser

    Changkun Chen, Christophe Nicolet, Koichi Yonezawa, Mohamed Farhat, Francois Avellan, Kazuyoshi Miyagawa, Yoshinobu Tsujimoto

    International Journal of Fluid Machinery and Systems   Vol.3 ( No.1 ) 91 - 101  2010.01

    DOI CiNii

  • Dynamic Characteristics of the Radial Clearance Flow between Axially Oscillating Rotational Disk and Stationary Disk

    H.Horiguchi, Y.Ueno, K.Takahashi, K.Miyagawa, Y.Tsujimoto

    International Journal of Fluid Machinery and Systems   Vol.2 ( No.2 ) 147 - 155  2009.04

    DOI

  • DYNAMIC CHARACTERISTICS OF THE RADIAL CLEARANCE FLOW BETWEEN AXIALLY OSCILLATING ROTATIONAL DISK AND STATIONARY DISK

    Hironori Horiguchi, Yoshinori Ueno, Koutaro Takahashi, Kazuyoshi Miyagawa, Yoshinobu Tsujimoto

    PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 1, PTS A-C   1 ( PART A ) 243 - 251  2009  [Refereed]

     View Summary

    Dynamic characteristics of the clearance flow between an axially oscillating rotational disk and a stationary disk were examined by experiments and computations based on a bulk flow model. In the case without pressure fluctuations at the inlet and outlet of the clearance, parallel and contracting flow paths had an effect to stabilize the axial oscillation of the rotating disk. The enlarged flow path had an effect to destabilize the axial oscillation due to the negative damping and stiffness for outward and inward flows, respectively. It was shown that the fluid force can be decomposed into the component caused by the inlet or outlet pressure fluctuation without the axial oscillation and that due to the axial oscillation without the inlet or outlet pressure fluctuation. A method to predict the stiffness and damping coefficients is proposed for general cases when the device is combined with an arbitrary flow system.

    DOI

  • Dynamic Characteristics of the Radial Clearance Flow Between Axially Oscillating Rotational Disk and Stationary Disk

    HORIGUCHI Hironori, UENO Yoshinori, TAKAHASHI Koutarou, MIYAGAWA Kazuyoshi, TSUJIMOTO Yoshinobu

    Turbomachinery   37 ( 1 ) 52 - 62  2009

     View Summary

    Dynamic characteristics of the clearance flow between a rotating and axially oscillating disk and a static disk were examined by experiments and numerical simulations based on a bulk flow model. In the case without pressure fluctuations at the inlet and outlet of the clearance, parallel and contracting flow paths had an effect of stabilizing the axial oscillation of the rotating disk. The enlarged flow path had an effect of destabilizing the axial oscillation due to the negative damping and stiffness for outward and inward flows, respectively. It was shown that the fluid force can be decomposed into the component caused by the inlet or outlet pressure fluctuation without the axial oscillation and that due to the axial oscillation without the inlet or outlet pressure fluctuation. A method to predict the stiffness and damping coefficients is proposed for general cases when the clearance is combined with an arbitrary flow system.

    DOI CiNii J-GLOBAL

  • Study on Internal Flow and New Design Technology for a Francis Turbine Runner

    K.Miyagawa, K.Yasuda, Y.Iwasaki

    Proceeding of 20th IAHR Symposium on Hydraulic machinery and systems    2008.08

  • ターボ機械インペラ、ブレードの製造技術

    宮川和芳

    ターボ機械   Vol,36 ( No.5 ) 1 - 2  2008.05

  • Kenkyu sokuho [Large-eddy simulation of non-cavitating and cavitating flows in the draft tube of a Francfis turbine]

    Guo Yang, Kato Chisachi, Miyagawa Kazuyoshi

    Monthly journal of the Institute of Industrial Science, University of Tokyo   59 ( 1 ) 83 - 88  2007.01

     View Summary

    &nbsp;&nbsp;&nbsp;The flow field in the draft tube of a Francis turbine model was calculated by using Large-Eddy Simulation (LES). At first, the non-cavitating flow in the draft tube was computed and the results using two different computational models (draft tube without runner and draft tube with runner) are compared. Based on the above comparison, the computational model of draft tube with runner was used to compute cavitating flows at two cavitation numbers: one is at the plant cavitation number; the other is lower than the plant cavitation number. The cavitation phenomena in the draft tube can be predicted qualitatively. [This abstract is not included in the PDF]

    DOI CiNii

  • Development of high performance oxidizer turbo-pump

    J. Takida, K. Yoshikawa, A. Ogawara, M. Atsumi, K. Miyagawa, K. Kobayashi, T. Miyawaki

    Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference   5   4870 - 4876  2007

     View Summary

    In order to develop a high performance turbo-pump which consists of many components such as pump, turbine, bearings, shaft seals, etc., it is necessary not only to improve the performance of such component but also to reach good balance in performance and strength as a system, in other words, integration of performance and reliability is important. Efficiency of turbo-pump for rocket engines is generally around 30%, and its performance does not usually become a problem for the engine system. An important thing is to reduce an unstable dynamic load by cavitation of a pump. In addition, it is also important that there is an enough operation margin for components such as shaft seals and bearings. Mitsubishi Heavy Industries (MHI) has developed an oxidizer turbo-pump in the in-house research program. Through this development, new approach was tried for these problems. In this paper, the technical feature of this oxidizer turbo-pump and the results of component tests and turbo-pump tests are presented. The development approach for the oxidizer turbo-pump enabled achievement of the stable operation of the oxidizer turbo-pump in a short development period and few tests, and its effectiveness has demonstrated.

  • Prediction method of required time of the siphon formation with numerical simulation

    K.Tanaka, I.Ishida, S.Yamane, K.Miyagawa, K.Kobayashi

    Proceeding of 23rd IAHR Symposium on Hydraulic machinery and systems    2006.10

  • Mitigation of draft tube flow instability with auxiliary parts in high head pump-turbine

    K.Miyagawa, T.Sano, N.Kunimatsu, T.Aki, M.Nishi

    Proceeding of 23rd IAHR Symposium on Hydraulic machinery and systems    2006.10

  • Large-eddy simulation of non-cavitating and cavitating flows in an elbow draft tube

    Y.Guo, C.Kato, K.Miyagawa

    Proceeding of 23rd IAHR Symposium on Hydraulic machinery and systems    2006.10

  • High temperature NPSH and its application for a feedwater system

    J Manabe, K Miyagawa

    JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING   49 ( 2 ) 352 - 359  2006.05

     View Summary

    Eight hundred MWe class PWR turbine-generators operated smoothly and continuously at sudden load reduction, from full load to house load, maintaining NPSH of the feedwater booster pumps through transition even though the available NPSH never exceeded zero. NPSH of the pump at 151.3 degrees C, at which the available NPSH was minimal during transition, was evaluated as a slightly negative value, in spite of a positive value at room temperature, applying both the Ruggeri-Moore method extended to the negative area on condition of gas venting out of the system, using data of both room temperature and 95 degrees C of a model pump facility, and another restriction by gas presence at the impeller inlet. The above evaluated high temperature NPSH demonstrated successful operation of the units equipped with a low static suction head yielding zero available NPSH during transition, resulting in alteration of the design criteria of the feedwater system and thereby contributing to possible cost reduction.

    DOI

  • CFDによるターボ機械流体関連振動の解明

    宮川和芳

    ターボ機械   56th ( No.1 ) 27 - 34  2006

    J-GLOBAL

  • High Temperature NPSH and Its Application for a Feed water System

    J.Manabe, K.Miyagawa

    Proceeding of 13th International Conference on Nuclear Engineering (ICONE13)    2005.05

  • 高信頼性を実現するロケットエンジン用機器の設計技術

    吉川公人, 小河原彰, 宮川和芳, 赤沢公雄, 稲田満

    三菱重工技報   42 ( 5 ) 238 - 241  2005

    CiNii J-GLOBAL

  • Study on stay vane instability due to vortex shedding

    K.Miyagawa, S.Fukao, Y.Kawata

    Proceeding of 22nd IAHR Symposium on Hydraulic machinery and systems    2004.06

  • Study of Internal Flow and Performance Improvement for Centrifugal Pump

    K.Miyagawa, S.Aoki, T.Osada

    Proceeding of 22nd IAHR Symposium on Hydraulic machinery and systems    2004.06

  • Numerical Analysis of unstable phenomena and stabilizing modification of an impeller in a centrifugal pump

    M.Iino, K.Tanaka, K.Miyagawa, T.Okubo

    Proceeding of 22nd IAHR Symposium on Hydraulic machinery and systems    2004.06

  • 地球温暖化抑制に有効な高効率水車の開発

    宮川和芳, 前川真丈, 福田暢英

    三菱重工技報   41 ( 3 ) 166 - 169  2004

    CiNii J-GLOBAL

  • Application of CFD Methodology to the Development of Turbomachinery

    内田澄生, 宮川和芳, 古賀淳

    ターボ機械   32 ( 5 ) 274 - 279  2004

    DOI CiNii J-GLOBAL

  • Water turbine subcommittee report. Development and introduction of a new-model runner in the Motokawa power plant.

    久保典彦, 岩崎純弘, 宮川和芳

    ターボ機械   32 ( 11 ) 644 - 647  2004

    DOI CiNii J-GLOBAL

  • Study of vibration mechanism for hydraulic turbine stay vanes

    K.Miyagawa, Y.Kawata, Y.Iwasaki

    Proceeding of 7th AICFM    2003.10

  • Study of cavitation erosion on hydraulic turbine runner

    M.Maekawa, K.Miyagawa

    Proceeding of 5th International Symposium on cavitation, CAV2003    2003.10

    CiNii

  • Physical modeling and simulation of leading edge cavitation application to an industrial inducer

    Y.A.Bouziad, M.Farhat, F.Avellan, K.Miyagawa

    Proceeding of 5th International Symposium on cavitation, CAV2003    2003.10

    CiNii

  • Application method of runner with splitter blade for improvement of ancillary services by using reversible pump-turbine

    M.Inagaki, N.Umeda, K.Miyagawa, T.Namba

    Proceeding of 7th AICFM    2003.10

  • Numerical simulation of hysteresis on head/discharge characteristics of a centrifugal pump

    M.Iino, K.Tanaka, K.Miyagawa, T.Ookubo

    Proceeding of 4th ASME-JSME Joint Fluids Engineering Conference   2 B   1165 - 1172  2003.06

     View Summary

    The objectives of the present study were to investigate influences of fins, set in a suction part, on the positive slope and hysteresis loop in head/discharge characteristic curves of centrifugal pumps in the experiment as well as in the numerical prediction. The fins were located in upstream side of a pump impeller to suppress swirl flow occurring before the impeller inlet at partial load operation. We had two kinds of centrifugal pump with/without the fins, the number of which is 16. These two centrifugal pumps had a shrouded impeller with 7 blades and a diffuser with 20 guide vanes with the same configuration. In the experiment, the pump with them had a large hysteresis loop at partial load operation in the head/discharge characteristic curve, although the pump without them had no hysteresis loop. In the numerical simulation based on periodic flow, the incompressible turbulent flow field was calculated for partial blade-passages with periodic boundary conditions. As a result, the simulated characteristics had the same tendencies as the experimental results. Furthermore, the causes of the discontinuous head/discharge characteristics depending on the direction of partial load operation were clarified through calculating and comparing the internal flow fields in the cases with/without the fins. The pumps had the large backflow and recirculation areas in two places, one of which was near the shroud at the impeller inlet including the fins area and another near the central part of the diffuser. The difference in the hysteresis loop between with and without the fins was caused by the existence of the fins, which suppressed or promoted the backflow at the impeller.

    DOI

  • Development of a low noise pump by new design concept

    K.Miyagawa, R.Sato

    Proceeding of 4th ASME-JSME Joint Conference Fluid Engineering Division Summer Meeting   2 A   145 - 151  2003.06

     View Summary

    The Japan Defense Agency is conducting a project to develop a cavitation tunnel called the FNS (Flow Noise Simulator project)(1). The FNS was designed as a large cavitation tunnel with low background noise level to measure the noise of an object. In order to satisfy the low noise level for the FNS, it is important to develop a low noise pump. In the present study, several new design concepts were developed using CFD (Computational Fluid Dynamics) and these concepts and the pump performance were verified by model test. In developing low noise pump, it is important to avoid cavitation generation in all operating conditions. It is also important to reduce blade-passing influence due to blade row interaction between impeller and diffuser. To control unsteadiness by interaction, the axial gap between two blade rows was widened and viscous wake from the impeller was decreased. Many extensive parametric studies (e.g. blade sweep, number of blades) were conducted using three-dimensional CFD computations. The impeller developed for the FNS pump has seven blades, 4.3 m diameter and the stator downstream has nine blades. Several model tests were carried out to verify the design concept of the pump. I was confirmed that the noise level of the new design pump was decreased compared to a conventional industrial pump and efficiency was also improved.

    DOI

  • Experimental study on unstable characteristics of mixed-flow pump at low flow-rates

    Hiroshi Funakoshi, Hiroshi Tsukamoto, Koji Miyazaki, Kazuyoshi Miyagawa

    Proceedings of the ASME/JSME Joint Fluids Engineering Conference   1 A   609 - 614  2003

     View Summary

    Static and dynamic characteristics of a mixed flow pump were measured at low flow rate, where the steady characteristic curves show a positive slope. Unsteady flow was measured at upstream and downstream of impeller, as well as on the casing wall of diffuser passage by using a fast response five-hole pitot tube and semi-conductor type pressure transducers. Dynamic response of the pump to the sinusoidal change in flow rate was measured under constant rotational speed. As a result of the unsteady flow measurements, the positive slope of steady characteristic was found to be caused by the impeller tip separation, inlet backflow, and pre-rotation. Moreover, the dynamic characteristics of the pump were found to become unstable with the increased frequency of flow rate.

    DOI

  • ターボ機械を支える先進流動解技術

    内田澄生, 宮脇俊裕, 宮川和芳, 古賀淳, 石坂浩一, 茨木誠一

    三菱重工技報   40 ( 6 ) 336 - 339  2003

    CiNii J-GLOBAL

  • Numerical analysis of unstable phenomena in a centrifugal pump

    M.Iino, K.Tanaka, K.Miyagawa, T.Okubo

    Proceeding of 21st IAHR Symposium on Hydraulic machinery and systems,    2002.09

  • Flow instability in an elbow draft tube for a Francis pump-turbine

    K.Miyagawa, K.Tsuji, J.Yahara, Y.Nomura

    Proceeding of 21st IAHR Symposium on Hydraulic machinery and systems    2002.09

    CiNii

  • Study on Behavior in Draft Tube for Hydraulic Turbine

    MAEKAWA Masatake, MIYAGAWA Kazuyoshi, KAWATA Yutaka

    Turbomachinery.   30 ( 2 ) 12 - 17  2002.02

    CiNii

  • Study on Behavior in Draft Tube for Hydraulic Turbine.

    前川真丈, 宮川和芳, 川田裕

    ターボ機械   30 ( 2 ) 76 - 81  2002

     View Summary

    The final target of this research is to establish a method for optimizing the design of a draft tube that is installed to recover the static pressure of water flow discharged from a hydraulic turbine runner. For this purpose, detailed measurements of the draft tube internal flows were implemented by using a draft tube element model to make it easy to control the inlet swirl flows, and the measured data was compared with the result of the flow analysis. Since the static internal fl ow in the draft tube was accurately simulated with three-dimensional viscosity analysis using a turbulence model, it proved useful as a designing tool for clarifying flow phenomena. And it becomes clear that the internal flows and the characteristics are largely influenced by the inlet flow velocity distribution, so this fact must be taken into consideration when designing a runner.

    DOI CiNii J-GLOBAL

  • ランナ取替えによる既設水車のリパワリング技術の開発

    宮川和芳, 辻浩二, 三戸良介, 長瀧正隆, 国松直斗

    三菱重工技報   39 ( 3 ) 148 - 151  2002

    CiNii J-GLOBAL

  • Experimental Study on Unstable Characteristic of Mixed-Flow Pump

    UMETANI Takuo, TSUKAMOTO Hiroshi, FUNAKOSHI Hiroshi, MIYAZAKI Koji, MIYAGAWA Kazuyoshi, OKUBO Takeshi

    The Proceedings of Conference of Kyushu Branch   55th ( 0 ) 113 - 114  2002

    DOI CiNii J-GLOBAL

  • Numerical Analysis of Internal Flow in a Centrifugal Pump.

    飯野真成, 田中和博, 宮川和芳, 大久保剛

    日本機械学会年次大会講演論文集   2002 ( Vol.3 ) 185 - 186  2002

     View Summary

    In the present study, the head/discharge characteristics of a centrifugal pump depending on the direction of partial load operation have been investigated through calculating internal flow. Based on the hypothesis of axisymmetric flow, the numerical simulation on the incompressible turbulent flow has been carried out for partial blade-passages with periodic boundary conditions. In the numerical calculation, the data previously calculated at a little more or less discharge are given as the initial condition. In the numerical results at partial flow operations the pump has the large backflow and recirculation regions in three locations, one of which is near the casing at the impeller inlet, another of which around the fins and the other of which near the central part of the diffuser. The scale of these regions varies steeply under two partial flow operation points as the discharge increases or decreases. As a result, the hysteresis loop appears in the head/discharge characteristics curve depending on the direction of partial load operation.

    DOI CiNii J-GLOBAL

  • Development of High Head Reversible Pump-Turbine with Splitter Blade Runner

    K.Miyagawa, T.Namba, K.Ikeda, S.Watanabe

    Proceeding of 20th IAHR Symposium on Hydraulic machinery and systems    2000.08

  • Development of High Performance Hydraulic Turbine Based on New Design Concepts.

    宮川和芳, 小室隆信, 岩崎純弘, 安田国雄

    三菱重工技報   37 ( 1 ) 34 - 37  2000

    CiNii J-GLOBAL

  • 水車の性能予測と模型試験結果

    宮川和芳

    ターボ機械   Vol.27 ( No.9 ) 1 - 10  1999.09

  • Development of High Head Pump-Turbine with Splitter Blades.

    池田孝蔵, 渡部繁則, 宮川和芳, 松下広

    電気学会電力・エネルギー部門大会論文集   10th  1999

    J-GLOBAL

  • On the development of viscous solvers for computation of transient flows in turbomachines

    Alexander Wiedermann, Kazuyoshi Miyagawa, Tsuyoshi Eguchi

    International Journal of Rotating Machinery   5 ( 4 ) 251 - 261  1999

     View Summary

    This paper focuses on development and validation of a viscous solver for the computation of unsteady flows in turbomachinery blade rows and stages consisting of rotors and stators. The code has been evolved from steady-state single flow solvers developed by Wiedermann based on time-marching finite difference schemes. A two-equation eddy viscosity model is applied, and the wall boundary conditions are determined by the y+-distance of the first grid line away from the wall. For the solution of transient flow fields the original time-stepping algorithm is replaced by a time-accurate scheme. The emphasis of the code validation will be on blade-row interaction in a complete turbomachinery stage. A 3-D example will be discussed and those parameters evaluated which are important for actual blading design. © 1999 OPA (Overseas Publishers Association) N.V.

    DOI

  • Effect of Runner with Splitter Blade for Francis Turbine Performance Improvement.

    宮川和芳, 松下広

    ターボ機械   27 ( 6 ) 377 - 384  1999

    DOI CiNii J-GLOBAL

  • Study of Flow Phenomena in Spiral Casing and Double Circular Cascade of a Francis Turbine

    K.Miyagawa, Y.Kawata, H.Fukuda

    Proceeding of KSME-JSME Fluid Engineering Conference    1998.10

    CiNii

  • 広域エネルギー貯蔵システム技術に関する研究会(3.2 揚水発電)

    宮川和芳

    日本機械学会動力エネルギシステム部門報告書     3.2.1 - 3.2.19  1998.03

  • Future prospect of electric power storage technology. Pumped storage generation system.

    宮川和芳

    エネルギーレビュー   18 ( 5 )  1998

    J-GLOBAL

  • Internal Flow Investigation and High Performance Technology for Hydraulic Turbine and Pump Turbine.

    宮川和芳, 小室隆信

    三菱重工技報   35 ( 3 ) 166 - 169  1998

    CiNii J-GLOBAL

  • Development of a new-model water wheel with a support impeller.

    宮川和芳, 前川真丈, 片瀬勉, 浅井靖史

    ターボ機械協会講演会   39th   33 - 36  1997

    J-GLOBAL

  • Development of a high-head large capacity variable-speed Deriaz type pump-turbine.

    鈴木勝朋, 五月女淳一, 宮川和芳, 辻浩二

    ターボ機械協会講演会   38th  1997

    J-GLOBAL

  • 3D-Euler and Navier-Stokes Analysis of Flow Fields in Vaned Passages of Hydraulic Turbomachines

    A.Wiedermann, K.Miyagawa

    Proceeding of The 2nd ASIAN Computational Fluid Dynamics Conference (ACFD2)    1996.12

  • Application of Numerical Simulation for Turbomachinery Flow Analysis.

    宮脇俊裕, 宮川和芳, WIEDERMANN A, 渡辺英一郎, 関直之

    三菱重工技報   33 ( 4 ) 274 - 277  1996

    CiNii J-GLOBAL

  • “Recent pump trend”.Flow analysis technology for pumps.

    宮川和芳

    産業機械   ( 529 ) 16 - 19  1994

    J-GLOBAL

  • An Experimental Investigation of Fluid Exciting Force on a High Head Pump-Turbine Runner

    K.Miyagawa

    Proceeding of International Symposium on Rotating Machinery 4 ISROMAC-4   4   133 - 142  1992.07

    CiNii

  • An Experimental Investigation of Flows within Parallel Type Speed-Ring for Water Turbine.

    宮川和芳, 縄田秀夫, 小室隆信

    ターボ機械   20 ( 11 ) 718 - 723  1992

    DOI CiNii J-GLOBAL

  • 超高落差大容量ポンプ水車の開発研究

    神吉博, 宮川和芳

    三菱重工技報   Vol.28 ( No.6 )  1991.11

  • Development of Super High Head and Large Capacity Pump Turbine.

    神吉博, 牟田口弘造, 宮川和芳, 坂元篤, 岩崎純弘, 藤木繁登, 寺崎明, 古矢千吉

    三菱重工技報   28 ( 6 )  1991

    J-GLOBAL

▼display all

Books and Other Publications

  • 流体機械 : 基礎理論から応用まで

    山本, 誠, 太田, 有, 新関, 良樹, 宮川, 和芳

    共立出版  2018.10 ISBN: 9784320082205

Misc

  • オープンインペラを有する遠心ポンプのディフューザにおける非定常損失

    杉山大介, 市之瀬飛馬, 武田智貴, 稲葉夢乃, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   83rd  2020

    J-GLOBAL

  • 斜流ポンプ性能に対する前進スキュー角の影響

    生田晃浩, 陳奕寧, 八野田真也, 宮川和芳, 篠塚泰, 富松重行

    ターボ機械協会講演会(CD-ROM)   83rd  2020

    J-GLOBAL

  • デュアルカメラによる楕円形状キャビテーションロープの可視化

    劉志豪, ファブレルアーチャ, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   83rd  2020

    J-GLOBAL

  • 過給機用コンプレッサの脈動流下サージング挙動に関する実験的研究

    淺中祐志, 中村揚平, 榊原將至, 板垣悠太, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   83rd  2020

    J-GLOBAL

  • 〔生産統計〕2019年のターボ機械の動向と主な製作品

    宮川和芳, 宮川和芳, 矢田元治, 下川海, 安斉章, 田中宏明, 作田裕之, 奥野研一, 赤石裕二

    ターボ機械   48 ( 8 )  2020

    J-GLOBAL

  • Prediction of Fluid Exciting Force due to Cavitation

    宮川和芳, 伊賀由佳, 堀口祐憲, 川北千春

    ターボ機械   48 ( 9 )  2020

    J-GLOBAL

  • アンシュラウデッドランナを有するフランシス水車のLDV計測による内部流れ分析

    入江達也, 劉志豪, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   84th  2020

    J-GLOBAL

  • CFD-DEM解析による流体中での球状・非球状物質の挙動予測手法構築と斜流ポンプへの適用

    三浦健太郎, 近藤優樹, 宮川和芳, 末松潤一, 佐野岳志, 深尾伸次

    ターボ機械協会講演会(CD-ROM)   84th  2020

    J-GLOBAL

  • Unsteady Internal Flow and Loss Mechanism of a Turbocharger Turbine Under Pulsating Flow Condition

    中村揚平, 宮川和芳

    ターボ機械   48 ( 11 )  2020

    J-GLOBAL

  • Relation between Internal Flow and Loss Mechanism in an Unshrouded Impeller

    武田智貴, 市之瀬飛馬, 宮川和芳, 小川洋平, 根岸秀世

    航空原動機・宇宙推進講演会講演論文集(CD-ROM)   59th  2019

    J-GLOBAL

  • Flow Characteristics of a Balance Piston System in a Rocket Turbo Pump

    松本圭介, 吉村真美子, 林智之, 宮川和芳, 川崎聡, 平木博道, 須和直人

    航空原動機・宇宙推進講演会講演論文集(CD-ROM)   59th  2019

    J-GLOBAL

  • エンジンの排気脈動波形がターボチャージャタービン性能に及ぼす影響

    阿部勇大, 知念真渡, 榊原將至, 中村揚平, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   81st  2019

    J-GLOBAL

  • ハイブリッドユニットを負荷とする軸流型水力タービンシステムの構築

    安代和司, 中居俊介, 新保拓哉, 宮川和芳, 荒木力, 山岸直人, 杉本隆幸

    ターボ機械協会講演会(CD-ROM)   81st  2019

    J-GLOBAL

  • バランスピストンシステムの静特性,動特性の評価

    松本圭介, 吉村真美子, 林智之, 宮川和芳, 川崎聡, 平木博道, 須和直人

    ターボ機械協会講演会(CD-ROM)   81st  2019

    J-GLOBAL

  • エンジン熱効率50%に寄与した過給機システムの研究と開発

    中村揚平, 宮川和芳, 森吉泰生, 窪山達也, 田畑正和

    ターボ機械協会講演会(CD-ROM)   81st  2019

    J-GLOBAL

  • 各種ポンプの滑り係数の調査

    八野田真也, 武田智貴, 新田成輝, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   81st  2019

    J-GLOBAL

  • Research and Development on Utilizing Exhaust Gas Energy and Reducing Mechanical Losses by “Loss Reduction Team” in the SIP’s “Innovative Combustion Technologies”

    大聖泰弘, 宮川和芳, 飯田努, 三原雄司

    日本燃焼学会誌   61 ( 197 )  2019

    J-GLOBAL

  • Check list and the specific descriptions of the approval drawings and calculation sheets for hydraulic turbines, generators and accessories in hydropower plants

    中西裕二, 石川忠, 下鳥順文, 齋藤健一, 千葉和彦, 石黒友希夫, 高橋正宏, 宮川和芳, 山本広祐, 堀尾勝美, 久光敏彦, 福原正幸, 鈴村隆, 押味秀明, 伊藤義宏, 唐木俊明, 伊藤茂則, 栃井和彦, 二俣浩行, 中村智和, 阿黒克俊, 山本和生, 宇野真, 西原誠, 十河睦友, 金岡伸治, 岡嶋圭介, 福島晋, 國松和明, 森淳二, 町野毅, 小森健介, 亀岡孝弘, 横山弘志, 久芳史朗, 柳田将臣, 竹村正央, 村田丈和, 佐藤良祐, 脇坂純, 堀川祥吾, 古郡靖, 斎藤雅昭

    電気協同研究   75 ( 1 )  2019

    J-GLOBAL

  • 遠心羽根車隙間流れのLDV計測

    稲葉夢乃, 市之瀬飛馬, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   82nd  2019

    J-GLOBAL

  • ウォータージェット推進船の過渡,定常走行のポンプキャビテーション特性

    八野田真也, 生田晃浩, 宮川和芳, 逸見恭彦, 佐藤英吉, 川内清恵

    ターボ機械協会講演会(CD-ROM)   82nd  2019

    J-GLOBAL

  • 水中翼のフラッタ特性の把握及びキャビテーションによる影響評価

    峰島大誠, 中居俊介, 向井善郁, 宮川和芳, 川北千春, 白石耕一郎

    ターボ機械協会講演会(CD-ROM)   82nd  2019

    J-GLOBAL

  • 流体剛体連成解析を用いたティルティングパッドジャーナル軸受の特性予測手法の検討

    林智之, 松本圭介, 岩瀬文悟, 宮川和芳, 川口英晃, 千葉秀俊, 増田光

    ターボ機械協会講演会(CD-ROM)   82nd  2019

    J-GLOBAL

  • ターボ機械の非定常・非軸対称流れ 脈動流下におけるタービン,コンプレッサの性能と内部流れ

    宮川和芳, 中村揚平

    ターボ機械   46 ( 7 )  2018

    J-GLOBAL

  • 特殊用途タービン 潮流・海流発電用タービンの研究開発動向

    宮川和芳

    日本ガスタービン学会誌   46 ( 4 )  2018

    J-GLOBAL

  • 過給機一次元非定常流動モデルの構築と脈動流下特性の評価

    知念真渡, 中村揚平, 保井健佑, 山田翔, 榊原將至, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 遠心羽根車隙間流れと円板摩擦損失

    氏家隆太郎, 市之瀬飛馬, 中村揚平, 宮川和芳, 飯野真成, 浅原大輝, 佐野岳志

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 過給機コンプレッサの脈動流下特性と非定常損失

    榊原將至, 中村揚平, 山田翔, 保井健佑, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 水中翼のフラッタ特性の把握および安定限界の予測

    峰島大誠, 松田国将, 大西馨子, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 円板摩擦損失特性と渦構造

    飯野真成, 浅原大輝, 佐野岳志, 氏家隆太郎, 中村揚平, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 磁気軸受加振試験装置を用いたジャーナル軸受の振動特性の測定と評価

    林智之, 竹中健一郎, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   79th  2018

    J-GLOBAL

  • 遠心羽根車の翼列干渉の特徴

    劉志豪, 宮川和芳, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   80th  2018

    J-GLOBAL

  • 自動車用ターボチャージャタービンの内部流れ分析による設計最適化

    中村揚平, 知念真渡, 榊原將至, 宮川和芳, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   80th  2018

    J-GLOBAL

  • ディフューザ内流動不安定現象のキャビテーションによる影響

    久保雅史, 劉志豪, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   80th  2018

    J-GLOBAL

  • 内部流れの把握による軸流ウォータージェットポンプの性能向上

    前田聡, 宮川和芳, 宮川和芳, 逸見恭彦, 佐藤英吉

    ターボ機械協会講演会(CD-ROM)   80th  2018

    J-GLOBAL

  • 過給機用圧縮機の脈動下特性と内部流れ

    榊原將至, 宮川和芳, 中村揚平, 山田翔, 保井健佑

    日本機械学会関東支部総会・講演会講演論文集(CD-ROM)   24th  2018

    J-GLOBAL

  • 遠心形ディフューザポンプの動静翼列間距離による性能と内部流れの変化

    氏家隆太郎, 小牧秀太郎, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 無閉塞ポンプ閉塞メカニズム解明のための繊維状物質の挙動予測

    今坂大和, 金井裕明, 菅野仁史, 斉藤純夫, 宮川和芳, 能見基彦, 磯野美帆, 打田博, 川井政人

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 車両過給機用タービンの脈動流下における非定常内部流れと損失メカニズム

    中村揚平, 白鳥早紀, 保井健佑, 山田翔, 知念真渡, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 圧縮性を考慮した液体水素解析による遠心羽根車の内部流れに関する検討

    吉村真美子, 木村徳夫, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 三段遠心ポンプにおける回転-静止系間隙間が軸スラストに及ぼす影響

    古川大地, 高峯大輝, 渡邉聡, 渡邉啓悦, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 比速度160m-kWシュラウドレス水車の内部流れおよび損失メカニズム

    進士昌史, 劉志豪, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   77th  2017

    J-GLOBAL

  • 水車ドラフトチューブの内部流れの予測と評価

    湯川達人, 進士昌史, 惣中康太, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   78th  2017

    J-GLOBAL

  • 遠心形ディフューザポンプにおけるディフューザ設計指針の検討

    吉村真美子, 木村徳夫, 市之瀬飛馬, 林智之, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   78th  2017

    J-GLOBAL

  • 遠心形ターボ機械における軸方向推力調整機構の動特性予測の高精度化

    木村徳夫, 吉村真美子, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   78th  2017

    J-GLOBAL

  • ディフューザポンプ内部流れの構造評価

    市之瀬飛馬, 木村徳夫, 吉村真美子, 林智之, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   78th  2017

    J-GLOBAL

  • Unsteady Flow Characteristic under Pulsating flow for Turbocharger

    NAKAMURA Yohei, YAMADA Sho, YASUI Kensuke, CHINEN Manato, MIYAGAWA Kazuyoshi

    The Proceedings of Mechanical Engineering Congress, Japan   2017 ( 0 ) G0500601  2017

     View Summary

    <p>The turbine gas inflow in a turbocharger exhibits pulsating behavior because of the opening and closing of engine valves. Turbocharger data for engine design is usually computed for steady flow conditions. However actual turbochargers operate under pulsating flow which is reported to decrease turbine efficiency. In this study, experimental investigation and Computational Fluid Dynamics (CFD) under pulsating flow condition were performed. Unsteady performance measurement and Particle Image Velocimetry (PIV) measurement were performed by using a model turbine test rig. RANS and DES were used. On the computational side, it was noted that DES is needed to simulate the flow pattern of a turbine outlet under pulsating flow.</p>

    DOI CiNii J-GLOBAL

  • Application of Unsteady Flow Measurement for Turbomachine Development

    MIYAGAWA Kazuyoshi

    The Proceedings of Mechanical Engineering Congress, Japan   2017 ( 0 ) W053003  2017

    DOI CiNii J-GLOBAL

  • Fluid Excitation Forces in Turbomachinery

    宮川和芳, 内海政春

    Turbomachinery   45 ( 5 ) 293 - 303  2017

    J-GLOBAL

  • 水力発電所付属設備の設計指針

    中西裕二, 米沢比呂志, 佐藤正, 久保和俊, 三根浩二, 福島晋, 篠原朗, 宮川和芳, 足立和郎, 高島和信, 堀尾勝美, 千葉治仁, 石川忠, 上野卓也, 福原正幸, 築山由明, 西畠英治, 老田爾, 二俣浩行, 村上睦, 庄野弘高, 野村喜久, 十河睦友, 落合勉, 石黒友希夫, 鈴木彰, 中嵜秀則, 浅沼孝祐, 岩田大司, 秋田健司, 横山弘志, 町野毅, 小森健介, 高橋正宏, 福澤正之, 柴田直俊, 亀岡孝弘, 出原拓哉, 池野清志, 松井収, 西岡宗光, 中澤紳浩, 中村尚碁, 山本謙治, 山口剛, 加藤敦, 飯田賢治, 田所利一, 上野登, 西野清則, 古郡靖, 山下龍夫, 松尾和宏

    電気協同研究   72 ( 1 )  2016

    J-GLOBAL

  • 翼後縁から生じる非定常渦の解析手法についての研究

    細野和樹, 梶江雄太, 宮川和芳, 山田卓慶, 川北千春

    ターボ機械協会講演会(CD-ROM)   75th  2016

    J-GLOBAL

  • 相反転ジャーナル軸受の特性予測に関する研究

    竹中健一郎, 北内征士朗, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   75th  2016

    J-GLOBAL

  • 脈動流下における遠心タービンの非定常挙動に関する研究

    中村揚平, 白鳥早紀, 保井健佑, 山田翔, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   75th  2016

    J-GLOBAL

  • 相反転タービンに生じる流体励振力の評価手法に関する研究

    松田国将, 梶江雄太, 細野和樹, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   75th  2016

    J-GLOBAL

  • 多段遠心ポンプに作用する流体力と不安定現象に関する研究(ライナリング隙間等間隙部の寸法の影響)

    古川大地, 高峯大輝, 渡邉聡, 渡邉啓悦, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   76th  2016

    J-GLOBAL

  • 遠心ポンプディフューザの低流量域での内部流れと流動不安定

    小牧秀太郎, 平松英人, 氏家隆太郎, 宮川和芳, 佐野岳志

    ターボ機械協会講演会(CD-ROM)   76th  2016

    J-GLOBAL

  • 三段遠心ポンプに生じるディフューザ失速に関する研究

    古川大地, 高峯大輝, 渡邉聡, 渡邉啓悦, 宮川和芳

    日本機械学会年次大会講演論文集(CD-ROM)   2016  2016

    J-GLOBAL

  • Rotating Stall Characteristics in Off Design Condition of a Centrifugal Pump

    SHIBATA Akiha, HIRAMATSU Hideto, KOMAKI Syutaro, MIYAGAWA Kazuyoshi

    Turbomachinery   44 ( 4 ) 216 - 222  2016

     View Summary

    <p>Downsizing and improvement of efficiency in a centrifugal pump have been required still now. It is well known that the flow instability such as a positive slope in Q-H curve, rotating stall often may appear in case of the above advanced design. Though a lot of studies of flow instability in a pump were carried out by experimental and computational approaches up to now, this generating mechanism was not clarified quantitatively.</p><p> In this study, we made the one stage model test facility for measuring both the performance and the internal flow. By use of this test facility, we found the rotating stall in the diffuser influences the positive slope mechanism in Q-H curve. The characteristics of the rotating stall were clarified by experiments and computations. The simulation results have good agreement with the experiments quantitatively.</p>

    DOI CiNii J-GLOBAL

  • 1614 Vaned-diffuser rotating stall and radial thrust fluctuation in a three-stage centrifugal pump

    FURUKAWA Daichi, WATANABE Satoshi, HARA Yoshinori, YAMASHITA Tetsuya, WATANABE Hiroyoshi, MIYAGAWA Kazuyoshi

    Fluids engineering conference ...   2015   "1614 - 1"-"1614-3"  2015.11

     View Summary

    In this study, the effect of the rotor axial offset and impeller-diffuser gap (smaller gap or larger gap) on the performances and the unsteady thrust forces of a three stage centrifugal pump were experimentally investigated. The change of the gap was realized by cutting an impeller diameter. By cutting the impeller diameter (larger gap) the positive slope of the head performance curve was observed in lower flow rates than 20% of design flow rate, while it was not observed with the smaller gap. In the flow rate range with the positive slope, the distinct pressure fluctuation with low frequency (14% of impeller rotation), measured at the inlet throat of diffuser vane, could be recognized, which was found to be caused by the diffuser rotating stall with 1 cell. The unsteady radial thrust force caused by the diffuser rotating stall was observed at the same time. The rotating stall was more significantly observed in the 3rd stage, which was probably because the test pump system employed the balancing drum for the thrust balancing device; the effective flow rate is larger in the 1st and 2nd stage diffusers than the 3rd one due to the leakage flow to the balancing drum just upstream of the 3rd stage diffuser.

    CiNii

  • 1203 Acoustic Resonance Phenomenon Induced by Rotor and Stator Interaction of Diffuser Pump

    HIRAMATSU Hideto, KOMAKI Shutaro, MIWA Maremi, MIYAGAWA Kazuyoshi, KIMURA Norio

    Fluids engineering conference ...   2015   "1203 - 1"-"1203-4"  2015.11

     View Summary

    In plants, pressure fluctuation in specific frequency occurs by operating fluid machinery such as a pump. If the frequency is consistent with that of pipe liquid resonance, the large vibration of the pipe and machinery may be induced. In this study, unsteady pressure in an air test model of diffuser pump was measured to clarify the generating mechanism of the pressure fluctuations. It is found that there are two types of resonances, "air column resonance" and "pressure fluctuation induced by rotor stator interaction". Moreover, it is clarified that the pressure fluctuation by resonance is decreased by setting an orifice at a node of a standing wave by echo sound test using a speaker. Also it is clarified that the smaller opening ratio of the orifice is, the larger the pressure fluctuation is decreased.

    CiNii

  • 多段遠心ポンプ軸系に作用する軸方向・半径方向スラスト特性に関する研究

    山下徹也, 古川大地, 渡邉聡, 原義則, 渡邉啓悦, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   73rd  2015

    J-GLOBAL

  • シュラウドレスフランシス水車の内部流れと損失発生メカニズムの研究

    白鳥早紀, 島諒介, 小松啓樹, 中島峻浩, 中村揚平, 松坂龍, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   73rd  2015

    J-GLOBAL

  • 中小容量向け新型水車の開発と運転

    國分清, 西川雄基, 稲垣守人, 村椿仁, 矢澤省匡, 島諒介, 小松啓樹, 中村揚平, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   73rd  2015

    J-GLOBAL

  • 軸流ポンプのキャビテーションによる非定常現象

    梶江雄太, 福士容平, 斉藤純夫, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   73rd  2015

    J-GLOBAL

  • 《ターボ機械HPCプロジェクト~その概要と得られた成果~》多段ポンプの非定常計算

    渡邉啓悦, 渡邉聡, 宮川和芳, 山出吉伸

    ターボ機械   43 ( 9 )  2015

    J-GLOBAL

  • 1203 Acoustic Resonance Phenomenon Induced by Rotor and Stator Interaction of Diffuser Pump

    HIRAMATSU Hideto, KOMAKI Shutaro, MIWA Maremi, MIYAGAWA Kazuyoshi, KIMURA Norio

    The Proceedings of the Fluids engineering conference   93rd ( 0 ) _1203 - 1_-_1203-4_  2015

     View Summary

    In plants, pressure fluctuation in specific frequency occurs by operating fluid machinery such as a pump. If the frequency is consistent with that of pipe liquid resonance, the large vibration of the pipe and machinery may be induced. In this study, unsteady pressure in an air test model of diffuser pump was measured to clarify the generating mechanism of the pressure fluctuations. It is found that there are two types of resonances, "air column resonance" and "pressure fluctuation induced by rotor stator interaction". Moreover, it is clarified that the pressure fluctuation by resonance is decreased by setting an orifice at a node of a standing wave by echo sound test using a speaker. Also it is clarified that the smaller opening ratio of the orifice is, the larger the pressure fluctuation is decreased.

    DOI CiNii J-GLOBAL

  • 1614 Vaned-diffuser rotating stall and radial thrust fluctuation in a three-stage centrifugal pump

    FURUKAWA Daichi, WATANABE Satoshi, HARA Yoshinori, YAMASHITA Tetsuya, WATANABE Hiroyoshi, MIYAGAWA Kazuyoshi

    The Proceedings of the Fluids engineering conference   93rd ( 0 ) _1614 - 1_-_1614-3_  2015

     View Summary

    In this study, the effect of the rotor axial offset and impeller-diffuser gap (smaller gap or larger gap) on the performances and the unsteady thrust forces of a three stage centrifugal pump were experimentally investigated. The change of the gap was realized by cutting an impeller diameter. By cutting the impeller diameter (larger gap) the positive slope of the head performance curve was observed in lower flow rates than 20% of design flow rate, while it was not observed with the smaller gap. In the flow rate range with the positive slope, the distinct pressure fluctuation with low frequency (14% of impeller rotation), measured at the inlet throat of diffuser vane, could be recognized, which was found to be caused by the diffuser rotating stall with 1 cell. The unsteady radial thrust force caused by the diffuser rotating stall was observed at the same time. The rotating stall was more significantly observed in the 3rd stage, which was probably because the test pump system employed the balancing drum for the thrust balancing device; the effective flow rate is larger in the 1st and 2nd stage diffusers than the 3rd one due to the leakage flow to the balancing drum just upstream of the 3rd stage diffuser.

    DOI CiNii J-GLOBAL

  • International Conferences on Gas Turbines and Jet Engines

    NAKAMATA Chiyuki, OKAI Keiichi, KODAMA Hidekazu, GOTO Jinichiro, YAMANE Takashi, YAMAMOTO Makoto, OKI Yuso, HAMADA Hiroyuki, MIYAGAWA Kazuyoshi, MIYOSHI Ichiro

    Journal of the Gas Turbine Society of Japan   43 ( 1 ) 8 - 13  2015

    CiNii J-GLOBAL

  • 水車ドラフトチューブの不安定流動と抑制による性能への影響

    中島峻浩, 松坂龍, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   71st  2014

    J-GLOBAL

  • 中小水力向けシュラウドレスフランシス水車の開発

    中村揚平, 島諒介, 小松啓樹, 白鳥早紀, 斉藤純夫, 宮川和芳, 稲垣守人, 長谷川義晃, 岡本聡, 笠原強造, 村椿仁, 國分清, 西川雄基, 八尾泰弘, 子安玲

    ターボ機械協会講演会(CD-ROM)   72nd  2014

    J-GLOBAL

  • ロケットターボポンプ用バランスピストンの特性に関する研究

    吉井悠貴, 内山建吾, 木村徳夫, 柴田晶羽, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   72nd  2014

    J-GLOBAL

  • 軸流ポンプの羽根車内部流れに関する研究

    梶江雄太, 福士容平, 細野和樹, 斉藤純夫, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   72nd  2014

    J-GLOBAL

  • 翼列干渉によるインペラ励振力および軸振動の検討

    平松英人, 柴田晶羽, 小牧秀太郎, 宮川和芳, LIMING Zhai, 佐野岳志

    ターボ機械協会講演会(CD-ROM)   72nd  2014

    J-GLOBAL

  • 遠心ポンプ低流量域の旋回失速による損失発生メカニズムの研究

    柴田晶羽, 平松英人, 小牧秀太郎, 宮川和芳, 前田学, 佐野岳志, 飯野真成, 亀井瞬, 間亮太

    ターボ機械協会講演会(CD-ROM)   72nd  2014

    J-GLOBAL

  • Modeling contact between solid surfaces with significant friction

    OKADA Naoya, KAWAI Masato, TAKIZAWA Kenji, HATTORI Hitoshi, Tezduyar Tayfun, MIYAGAWA Kazuyoshi, SAITO Sumio, ISONO Miho, NOUMI Motohiko, UTHIDA Hiroshi

    NCTAM papers, National Congress of Theoretical and Applied Mechanics, Japan   63 ( 0 ) 86 - 86  2014

     View Summary

    Flow in a sewage pump might carry many unpredictable solid objects. To understand better<br>how an object might wrap around the blades, we investigate the mechanism in a laboratory&nbsp;<br>model. The model consists of a cable and rigid obstacles. In the interaction between&nbsp;<br>the two, the friction forces play an important role because of the high friction coefficient&nbsp;<br>and the wrapping. To model this contact, we study it experimentally, measure the model&nbsp;<br>parameters, and test the model numerically.

    DOI CiNii

  • Preface for Special issue on Pump & Gasturbine

    MIYAGAWA Kazuyoshi

    Journal of the Gas Turbine Society of Japan   41 ( 3 ) 204 - 206  2013.05

    CiNii

  • ポンプの異物閉塞メカニズムと通過性評価方法の検討

    磯野美帆, 能見基彦, 打田博, 川井政人, 工藤大樹, 川原拓真, 宮川和芳

    ターボ機械協会講演会(CD-ROM)   70th  2013

    J-GLOBAL

  • 119 A study on measurment of drafttube dynamic characteristics

    YAMAMOTO Keita, YONEZAWA Koichi, Miyagawa Kazuyoshi, Avellan Francois, Doerfler Peter, TSUJIMOTO Yoshinobu

    The Proceedings of Conference of Kansai Branch   88th ( 0 ) _1 - 19_  2013

    DOI CiNii J-GLOBAL

  • 水力発電用水車の小型試験装置における部分流量・過大流量キャビテーションサージに関する研究

    米澤宏一, 小西大介, 宮川和芳, AVELLAN Francois, DOERFLER Peter, 辻本良信

    ターボ機械協会講演会   67th  2012

    J-GLOBAL

  • Partial Load and Over Load Cavitation Surges in a Small Model Test Facility for a Hydraulic Power Plant

    YONEZAWA Koichi, KONISHI Daisuke, MIYAGAWA Kazuyoshi, DOERFLER Peter, AVELLAN Francois, TSUJIMOTO Yoshinobu

    Turbomachinery   40 ( 12 ) 715 - 724  2012

     View Summary

    Model tests and CFD were carried out to find out the cause of cavitation surge in hydraulic power plants. In experiments the cavitation surge was observed at flow rates higher and lower than the swirl free flow rate, both with and without a surge tank placed just upstream of the inlet volute. An unsteady CFD was carried out with two boundary conditions:(1)the flow rate is fixed to be constant at the inlet volute, (2)the total pressure is kept constant at the volute inlet, corresponding to the experiments without/with the surge tank. The surge was observed with both boundary conditions at both higher and lower flow rates. Discussions as to the cause of the surge are made based on additional tests with an orifice at the diffuser exit, and with the diffuser replaced with a straight pipe.

    DOI CiNii J-GLOBAL

  • 2009年のターボ機械の動向と主な製作品

    坂口 順一, 岩崎 稔, 松本 貴與志, 安斎 章, 阿部 充, 宮川 和芳, 今村 博, 長尾 進一郎, 中村 憲司, 松谷 修, 川口 晃

    ターボ機械   38 ( 8 ) 492 - 509  2010.08

    CiNii

  • ドラフトチューブサージに及ぼす入口速度分布の影響

    米澤宏一, 田中さや香, 小西大介, 陳昌坤, 辻本良信, 宮川和芳

    ターボ機械協会講演会   63rd  2010

    J-GLOBAL

  • ドラフトチューブに生じるキャビテーション不安定に関する研究

    米澤宏一, 小西大介, 田中さや香, 辻本良信, 宮川和芳

    ターボ機械協会講演会   64th  2010

    J-GLOBAL

  • Manufacturing Technologies for Impeller and Blade of Turbomachinery

    MIYAGAWA Kazuyoshi, NAGAI Naoyuki

      36 ( 5 ) 257 - 258  2008.05

    CiNii

  • Flow Induced Vibrations of Turbomachinery

    MIYAGAWA Kazuyoshi

      36 ( 1 ) 10 - 10  2008.01

    CiNii

  • 高流量におけるドラフトチューブサージのモデル実験

    米澤宏一, 桑原康彰, CHEN C., 宮川和芳, 辻本良信

    ターボ機械協会講演会   60th  2008

    J-GLOBAL

  • W05 Will paradigm shift be made for fluid machinery research?

    GOTO Akira, TSUJIMOTO Yoshinobu, FURUKAWA Masato, KATO Chisachi, HAYAMI Hiroshi, MIYAGAWA Kazuyoshi, YAMANISHI Nobuhiro, ISOMURA Kosuke, TSUKAMOTO Hiroshi

    The Reference Collection of Annual Meeting   2008 ( Vol.9 ) 227 - 229  2008

    DOI CiNii J-GLOBAL

  • Application of CFD to FIV Research

    MIYAGAWA Kazuyoshi, FUKAO Shinji, MATSUYAMA Keisuke

    Turbomachinery   36 ( 1 ) 27 - 34  2008

    CiNii J-GLOBAL

  • 2007年のターボ機械の動向と主な製作品

    速水洋, 速水洋, 井上裕之, 原野正実, 宮川和芳, 鈴木日出夫, 高津恭, 今村博, 濱武久司, 井手紀彦, 萩原哲直, 今井善信

    ターボ機械   36 ( 8 ) 507 - 523  2008

    CiNii J-GLOBAL

  • 可変速モータ駆動圧縮機の曲げ-捩り連成振動

    時政泰憲, 長井直之, 山下勝也, 川島康弘, 北雅之, 畑谷岳志, 宮川和芳

    ターボ機械協会講演会   58th  2007

    J-GLOBAL

  • 1744 Analysis of Dynamic Characteristics of Clearance Flow in Balance Disk

    UENO Yoshinori, HORIGUCHI Hironori, TSUJIMOTO Yoshinobu, MIYAGAWA Kazuyoshi, TAKAHASHI Kotaro

    The proceedings of the JSME annual meeting   82nd ( 0 ) 395 - 396  2007

     View Summary

    Stiffness and damping coefficients of the clearance flow in balance disk models were measured in experiments and evaluated by calculations based on the bulk flow model. In the case of radially outward flow, it was found in experiments that the stiffness coefficient was negative in higher frequencies of axial oscillation in the parallel flow path and in all frequencies in the flow path which enlarged radially outward. In the case of radially inward flow, the stiffness coefficient was negative in the parallel flow path and the flow path which enlarged radially inward. The absolute values of the stiffness coefficient in the flow path which enlarged to the flow direction were larger than those in the parallel flow path.

    DOI CiNii J-GLOBAL

  • Analysis of Dynamic Characteristics of Clearance Flow in Balance Disk

    上野圭徳, 立川次元, 堀口祐憲, 辻本良信, 宮川和芳

    日本機械学会年次大会講演論文集   2007 ( Vol.2 ) _10 - 23_  2007

    DOI CiNii J-GLOBAL

  • 910 Analysis of Dynamic Characteristics of Clearance flow in Blance Disc

    SHIBATA Hideyoshi, UENO Yoshinori, HORIGUCHI Hironori, TSUJIMOTO Yoshinobu, MIYAGAWA Kazuyoshi

    The Proceedings of Conference of Kansai Branch   81st ( 0 ) _9 - 9_  2006

    DOI CiNii J-GLOBAL

  • 極低温流体用キャビテーション実験装置の製作

    田中禎一, 宮川和芳

    ターボ機械協会講演会   54th  2005

    J-GLOBAL

  • THERMODYNAMIC EFFECT OF CAVITATION IN CENTRIFUGAL PUMP FOR A FEEDWATER SYSTEM

    深尾伸次, 宮川和芳, 真鍋純

    日本機械学会流体工学部門講演会講演論文集(CD-ROM)   83rd ( 0 ) 222 - 222  2005

    DOI CiNii J-GLOBAL

  • 回流水槽向け低騒音ポンプの開発

    宮川和芳, 南部和幸, 佐藤隆一

    ターボ機械協会講演会   52nd  2004

    J-GLOBAL

  • ボイラ給水ポンプにおける羽根車後縁形状と右上がり特性

    飯野真成, 大倉裕嗣, 田中和博, 宮川和芳

    ターボ機械協会講演会   52nd  2004

    J-GLOBAL

  • ターボポンプインデューサの特性に関する研究

    小林一太, 宮川和芳, 川田裕, 渥美正博, 吉川公人, 滝田純也

    ターボ機械協会講演会   51st  2004

    J-GLOBAL

  • 高性能液酸ターボポンプの開発

    宮川和芳, 宮脇俊裕, 小林一太, 川田裕, 渥美正博, 吉川公人, 安田正治, 滝田純也

    ターボ機械協会講演会   51st  2004

    J-GLOBAL

  • Numerical Analysis of Internal Flow with lmpeller Modification in a Centrifugal Pump

    IINO Masamichi, TANAKA Kazuhiro, MIYAGAWA Kazuyoshi, OKUBO Takeshi

    The Proceedings of the Fluids engineering conference   82nd ( 0 ) 21 - 21  2004

    DOI CiNii J-GLOBAL

  • Experimantal Study on Dynamic Characteristics of Mixed Flow Pump

    SUGIYAMA Shinji, TSUKAMOTO Hiroshi, MIYAZAKI Kouji, MIYAGAWA Kazuyoshi, WATANABE Fumito

    The Proceedings of the Fluids engineering conference   82nd ( 0 ) 25 - 25  2004

    DOI CiNii J-GLOBAL

  • 高落差ポンプ水車の軸スラストと隙間内流れ

    三戸良介, 宮川和芳, 黒川淳一, 松井純

    ターボ機械協会講演会   50th  2003

    J-GLOBAL

  • 入口フィンが遠心ポンプ不安定現象に及ぼす影響

    飯野真成, 田中和博, 宮川和芳, 大久保剛

    ターボ機械協会講演会   50th  2003

    J-GLOBAL

  • ポンプ水車ランナ取替による運転範囲の拡大

    矢原二郎, 宮川和芳, 辻浩二

    ターボ機械協会講演会   50th  2003

    J-GLOBAL

  • Numerical Analysis of Internal Flow with Effect of Volute Casing in a Centrifugal Pump

    飯野真成, 田中和博, 宮川和芳, 大久保剛

    日本機械学会年次大会講演論文集   2003 ( Vol.2 ) 5 - 6  2003

     View Summary

    In the present study, the effect of volute casing on the head/discharge characteristics with 2-step positive slope of a centrifugal pump has been investigated through calculating internal flow field. Based on the hypothesis of axisymmetric flow field, the numerical simulations on the incompressible turbulent flow have been carried out for partial-blade passages with periodic boundary conditions. As a model of the volute casing, a parallel diffuser or three volute casings with different configuration was prepared in the simulation. The result on each head/discharge characteristic curve has the same tendency as the experiment in the positive slope. At partial flow operation, the pumps with each model have the large backflow and recirculation regions in two locations, one of which is near the casing at the impeller inlet and the other near the central part of the diffuser. The scale of these regions varies steeply under two partial flow operation points as the discharge changes. The results show that the dominant factor of the positive slope is independents of the configuration of volute casing and exists in the upwind of volute casing.

    DOI CiNii J-GLOBAL

  • Performance Improvement of a Pump-Turbine by Guide Vane Individual Control

    久保田一正, 稲垣守人, 梅田成実, 宮川和芳, 難波輝晃

    日本機械学会年次大会講演論文集   2003 ( Vol.2 ) 87 - 88  2003

     View Summary

    In order to improve performance of a reversible pump-turbine, individual guide vane control was studied. First, selection of components and layout of these components were discussed, after that each guide vane opening to improve an efficiency and vortex rope in a partial flow were investigated. Servo valve and actuator has to be adopted to decrease the space and force to structures. Hydraulic performance is improved by guide vane individual control.

    DOI CiNii J-GLOBAL

  • 水力機械静止翼列の流体励振力と非定常応答 水車ステーベーンの振動発生メカニズム

    宮川和芳, 川田裕, 梅村直, 岩崎純弘, 小室隆信

    ターボ機械協会講演会   49th  2002

    J-GLOBAL

  • フランシス水車のキャビテーション壊食に関する研究

    前川真丈, 宮川和芳, 小室隆信, 渡辺和彦, 植松博, 石黒友希夫

    ターボ機械協会講演会   48th  2002

    J-GLOBAL

  • Unsteady Flow Simulation in a Draft Tube for a Pump-Turbine.

    宮川和芳, 三戸良介, 辻浩二

    日本機械学会関西支部定時総会講演会講演論文集   77th ( 0 ) _6 - 49_-_6-50_  2002

     View Summary

    In order to extend operation range of a reversible pump-turbine, it is important to increase vortex core stability in the draft tube specifically in partial load operation. It is clarified that the behavior of a vortex core is subjected to the runner outlet swirl intensity. Thus, the tangential velocity control at the outlet of the runner by modifying runner vane geometry is very effective to stabilize the vortex core. This mechanism was confirmed by the experiments up to now, but it is difficult to optimize the runner geometry at that time. CFD is now very useful tool for designing runner geometry to improve the performance. To simulate the behavior of a vortex core, unsteady flow computation has to be used. This paper describes the simulation by using the unsteady flow computation to investigate the vortex core behavior in a draft tube for a Francis pump-turbine.

    DOI CiNii J-GLOBAL

  • 三次元翼設計による遠心ポンプの性能向上

    宮川和芳, 川田裕, 小西揚, 南部和幸, 大久保剛

    ターボ機械協会講演会   46th  2001

    J-GLOBAL

  • ポンプ取水槽の流れ解析による渦予測

    前川真丈, 宮川和芳, 清田研治, 安田俊雄, 長田俊幸

    ターボ機械協会講演会   47th  2001

    J-GLOBAL

  • ランナ改修による水車の性能向上 大橋発電所ランナ取り替え工事

    国松直斗, 野村喜久, 十河睦友, 宮川和芳, 三戸良介, 辻浩二

    ターボ機械協会講演会   46th  2001

    J-GLOBAL

  • スプリッタ付きポンプ水車ランナの比速度別性能評価

    稲垣守人, 梅田成実, 宮川和芳, 難波輝晃

    ターボ機械協会講演会   47th  2001

    J-GLOBAL

  • Numerical Analysis of Unstable Phenomenon in a Mixed-flow Pump.

    飯野真成, 田中和博, 宮川和芳, 大久保剛

    日本機械学会流体工学部門講演会講演論文集   79th ( 101-1010 ) 132 - 132  2001

    DOI CiNii J-GLOBAL

  • スプリッタ付き超高落差ポンプ水車ランナの振動強度評価

    池田孝蔵, 渡部繁則, 難波輝晃, 宮川和芳, 松下広

    電気学会電力・エネルギー部門大会論文集   11th  2000

    J-GLOBAL

  • 三次元翼設計技術によるフランシス水車の効率向上

    宮川和芳, 岩崎純弘, 安田国雄

    ターボ機械協会講演会   44th  2000

    J-GLOBAL

  • W08-(2) CFD の水車設計への適用

    宮川 和芳

    年次大会資料集   2000 ( 0 ) _504 - 1_-_504-2_  2000

    DOI CiNii

  • Evaluation of Reliability for a Reversible Pump-Turbine Runner with Splitter Blades.

    宮川和芳, 難波輝晃, 金子康智, 松下広, 池田孝蔵, 渡部繁則, 梅田成実

    日本機械学会年次大会講演論文集   2000 ( Vol.4 ) 25 - 26  2000

     View Summary

    Analytical and experimental study has been carried out to verify the performance of pump-turbine runner with splitter blades for super high-head reversible pump-turbines, and the advantage of runner with splitter blades has been made clear from the view point of hydraulic performance. Besides the hydraulic performance, pump-turbine runners for super-high head pump turbines are required to have enough against severe operating condition generated under high pressure high peripheral speed. To evaluate the strength of pump-turbine runner with splitter blades, actual head test and numerical simulation was performed. In this paper, study of super high head pump-turbine runners with splitter blades from the view point of runner strength is described.

    DOI CiNii J-GLOBAL

  • Experimental Study on Unstable Characteristic of Water Jet Pump.

    塚本寛, 高橋範康, 中本立宙, 宮崎康次, 宮川和芳, 大久保剛

    日本機械学会年次大会講演論文集   2000 ( Vol.4 ) 33 - 34  2000

     View Summary

    Experimental study was done to investigate the mechanism of the so-called drooping characteristics of Water Jet Pump. The flow-field was measured at the impeller inlet and outlet. The unsteady pressure on the casing wall was measured, and moreover, the inner flow at off design point was studied. As a result of the present study, the reason of this instability was found to be the secondary flow and the pre-rotation caused by the secondary flow.

    DOI CiNii J-GLOBAL

  • インデューサに生じる高次のキャビテーションサージとこれに伴う応力変動

    本井久之, 小口英男, 長谷川恵一, 宮川和芳, 中辻弘幸, 内海政春, 橋本知之, 堀口祐憲, 辻本良信

    ターボ機械協会講演会   45th   118 - 123  2000

    J-GLOBAL

  • スプリッタブレード付ポンプ水車の性能評価

    池田孝蔵, 渡部繁則, 宮川和芳, 松下広

    ターボ機械協会講演会   42nd  1999

    J-GLOBAL

  • Internal Flow in a Impeller of a Centrifugal Pump.

    宮川和芳, 今村広嗣, 川田裕, 南部和幸, 小西揚, 大久保剛

    日本機械学会年次大会講演論文集   1999 ( Vol.4 )  1999

    J-GLOBAL

  • Present state and future prospects of pumped storage power generation technology.

    宮川和芳, 小室隆信

    日本機械学会年次大会講演論文集   1999 ( Vol.4 )  1999

    J-GLOBAL

  • Secondary Flow in a Vaned Diffuser of a Centrifugal Pump.

    宮川和芳, 今村広嗣, 川田裕, 南部和幸, 小西揚, 大久保剛

    日本機械学会流体工学部門講演会講演論文集   1999  1999

    J-GLOBAL

  • Effect of Blade Row Interaction in a Francis Turbine.

    宮川和芳, 今村広嗣, 川田裕

    日本機械学会流体工学部門講演会講演論文集   1999  1999

    J-GLOBAL

  • ハイドロタービン性能予測分科会に参加して

    宮川 和芳

    ターボ機械   26 ( 7 ) 426 - 428  1998.07

    CiNii

  • Internal Flow in a Runner of a Francis Turbine(Viscous Effect).

    宮川和芳, 前川真丈, 川田裕

    日本機械学会流体工学部門講演会講演論文集   1998  1998

    J-GLOBAL

  • Development of a new type hydroturbine with subsidiary runner.

    宮川和芳, 前川真丈, 片瀬勉, 浅井靖史

    日本機械学会通常総会講演会講演論文集   75th ( 3 )  1998

    J-GLOBAL

  • Development of Long-lived Type Inducer.

    前田学, 宮川和芳, 田川雅士

    日本機械学会関西支部定時総会講演会講演論文集   73rd  1998

    J-GLOBAL

  • Internal Flow in a Runner of a Francis Turbine (Investigation of Loss Mechanism).

    宮川和芳, 今村広嗣, 川田裕

    日本機械学会全国大会講演論文集   76th ( Vol.3 )  1998

    J-GLOBAL

  • Design Technology of a Francis Turbine Double Circular Cascade using CFD.

    宮川和芳, 小室隆信

    日本機械学会通常総会講演会講演論文集   74th ( 1 )  1997

    J-GLOBAL

  • Research on cavitation of a water wheel with a support impeller.

    片瀬勉, 浅井靖史, 前川真丈, 宮川和芳

    ターボ機械協会講演会   39th  1997

    J-GLOBAL

  • Variable-Speed Pumped Storage Power Generation System used for the Deriaz type pump-turbine applied at high head and large power.

    鈴木勝朋, 五月女淳一, 辻浩二, 宮川和芳, 清水正憲

    電気学会電力技術研究会資料   PE-97 ( 63-68.70-73.75-77 ) 75 - 80  1997

    CiNii J-GLOBAL

  • Internal flow in a low flow rate region of a mixed flow pump.

    宮川和芳, 上原作一郎, 江口剛

    ターボ機械協会講演会   37th  1996

    J-GLOBAL

  • Grasping detailed flow at turbomachinery by incompressible, three-dimensional viscous flow analysis.

    宮川和芳, WIEDERMANN A, ERITT U

    ターボ機械協会講演会   32nd  1994

    J-GLOBAL

  • Development of a pump-turbine with a large head fluctuation margin.

    高橋公雄, 宮川和芳, 松下広

    ターボ機械協会講演会   32nd  1994

    J-GLOBAL

  • Unsteady response of turbomachinery cascade of blade by flow distortion.

    宮川和芳, 江口剛, 山口信行, 船崎健一

    ターボ機械協会講演会   33rd  1994

    J-GLOBAL

  • Experimental research on flow in a water turbine parallel speed ring.

    縄田秀夫, 宮川和芳, 森田浩之

    ターボ機械協会講演会   23rd  1989

    J-GLOBAL

▼display all

Industrial Property Rights

  • 流体機械の製造方法

    宮川 和芳, 高橋 航, 入江 達也

    Patent

    J-GLOBAL

  • キャビテーションエロージョン試験方法及び装置

    志賀 元泰, 佐藤 晴美, 奥 達也, 宮川 和芳, 斉藤 純夫

    Patent

    J-GLOBAL

  • ボルテックス形ポンプ用羽根車及びボルテックス形ポンプ

    磯野 美帆, 打田 博, 川井 政人, 宮川 和芳

    Patent

    J-GLOBAL

  • 液体機械

    稲垣 守人, 長谷川 義晃, 岡本 聡, 國分 清, 子安 玲, 宮川 和芳

    Patent

    J-GLOBAL

  • コーン、回転構造体及び流体機械

    特許第5495947号

    前川 真丈, 佐野 岳志, 宮川 和芳, 福田 暢英, 大川 公史, 渡辺 浩美, 岡本 展明, 矢野 博嗣

    Patent

    J-GLOBAL

  • 流体機械

    特許第5344838号

    佐野 岳志, 宮川 和芳

    Patent

    J-GLOBAL

  • ランナ及び流体機械

    特許第5230568号

    前川 真丈, 佐野 岳志, 宮川 和芳

    Patent

    J-GLOBAL

  • 渦励振抑制構造

    特許第5039821号

    松山 敬介, 宮川 和芳, 小西 揚

    Patent

    J-GLOBAL

  • 渦励振抑制構造

    特許第4928747号

    松山 敬介, 宮川 和芳, 小西 揚

    Patent

    J-GLOBAL

  • インペラの製造方法およびインペラ

    特許第4699531号

    渡部 裕二郎, ▲高▼谷 英明, 宮川 和芳, 益本 雅典

    Patent

    J-GLOBAL

  • 遠心ポンプ

    佐野 岳志, 江口 剛, 宮川 和芳, 小林 一太

    Patent

    J-GLOBAL

  • 水車およびその制御方法

    特許第4690702号

    宮川 和芳, 難波 輝晃, 梅田 成実

    Patent

    J-GLOBAL

  • ディフューザ

    特許第4658373号

    宮川 和芳, 大久保 剛

    Patent

    J-GLOBAL

  • 給水ポンプシステムの設計方法

    特許第4585517号

    真鍋 純, 宮川 和芳

    Patent

    J-GLOBAL

  • コーンおよび水車

    特許第4576414号

    宮川 和芳, 前川 真丈, 佐野 岳志, 国松 直斗, 森田 和彦, 岡本 展明

    Patent

    J-GLOBAL

  • インペラ、圧縮機およびインペラの製造方法

    中庭 彰宏, 渡部 裕二郎, 安井 豊明, 宮川 和芳, 紺野 勇哉

    Patent

    J-GLOBAL

  • 高温水ポンプの軸封装置

    特許第4468060号

    谷本 浩一, 中村 喜久男, 青木 素直, 川田 裕, 小室 隆信, 宮川 和芳, 犬塚 泰輔, 徳永 節男, 桑原 啓晃, 今井 聡, 小松 直隆

    Patent

    J-GLOBAL

  • 軸流ポンプ

    特許第4183612号

    宮川 和芳, 南部 和幸

    Patent

    J-GLOBAL

  • 人工心臓ポンプ

    特許第4108054号

    大久保 剛, 長田 俊幸, 佐野 岳志, 宮本 祐介, 宮川 和芳, 山本 康晴

    Patent

    J-GLOBAL

  • 軸流ポンプ

    特許第4107886号

    大久保 剛, 田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴, 佐野 岳志

    Patent

    J-GLOBAL

  • 人工心臓ポンプ

    特許第4084060号

    大久保 剛, 佐野 岳志, 田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴

    Patent

    J-GLOBAL

  • 軸スラストのバランス機構

    小林 一太, 安田 正治, 吉川 公人, 滝田 純也, 宮川 和芳, 深尾 伸次, 前川 真丈

    Patent

    J-GLOBAL

  • バランスディスクの安定化機構

    松山 敬介, 深尾 伸次, 宮川 和芳

    Patent

    J-GLOBAL

  • 渦励振抑制構造

    松山 敬介, 宮川 和芳, 小西 揚

    Patent

    J-GLOBAL

  • 流体機械の不安定流動抑制装置

    中庭 彰宏, 宮川 和芳

    Patent

    J-GLOBAL

  • ラビリンスシール及び当該ラビリンスシールを用いた回転機械

    特許第3820186号

    前川 真丈, 宮川 和芳, 佐久間 啓臣, 田代 光, 川田 裕

    Patent

    J-GLOBAL

  • 液中微生物処理装置

    佐野 岳志, 宮川 和芳, 小川 尚樹, 長田 俊幸, 大久保 剛, 阿武 智

    Patent

    J-GLOBAL

  • 遠心ポンプ

    特許第3771794号

    前川 真丈, 川田 裕, 小室 隆信, 宮川 和芳, 北島 直幸, 竹内 毅, 山本 康晴, 小西 揚

    Patent

    J-GLOBAL

  • インデューサ

    宮川 和芳, 小林 一太

    Patent

    J-GLOBAL

  • 給水ポンプシステム

    真鍋 純, 宮川 和芳

    Patent

    J-GLOBAL

  • 軸流ポンプ

    大久保 剛, 長田 俊幸, 佐野 岳志, 宮本 祐介, 宮川 和芳

    Patent

    J-GLOBAL

  • ポンプ水車

    特許第3706403号

    宮川 和芳, 松下 広

    Patent

    J-GLOBAL

  • 水車及びポンプ水車

    難波 輝晃, 藤森 貞暢, 宮川 和芳, 梅田 成実

    Patent

    J-GLOBAL

  • 人工心臓ポンプ

    大久保 剛, 長田 俊幸, 佐野 岳志, 宮本 祐介, 宮川 和芳, 山本 康晴

    Patent

    J-GLOBAL

  • 羽根車

    特許第3600449号

    渡部 繁則, 宮川 和芳, 今村 広嗣, 松下 広

    Patent

    J-GLOBAL

  • 水車

    前川 真丈, 宮川 和芳, 福田 暢英, 谷 英明

    Patent

    J-GLOBAL

  • 人工心臓ポンプおよび回転装置

    田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴, 佐野 岳志, 大久保 剛, 藤本 雅久

    Patent

    J-GLOBAL

  • 高温用ポンプ

    佐久間 啓臣, 宮川 和芳, 内海 晴輔, 久井 治, 中村 喜久男

    Patent

    J-GLOBAL

  • 水車用ランナ及び水車

    宮川 和芳

    Patent

    J-GLOBAL

  • 人工心臓ポンプ

    田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴, 佐野 岳志, 大久保 剛, 藤本 雅久

    Patent

    J-GLOBAL

  • 軸流ポンプ

    大久保 剛, 田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴, 佐野 岳志

    Patent

    J-GLOBAL

  • ポンプのディフューザ及びポンプ

    小林 一太, 宮川 和芳

    Patent

    J-GLOBAL

  • 人工心臓ポンプ

    大久保 剛, 佐野 岳志, 田川 雅士, 宮川 和芳, 長田 俊幸, 山本 康晴

    Patent

    J-GLOBAL

  • ポンプ水車の羽根車

    宮川 和芳, 難波 輝晃, 梅田 成実

    Patent

    J-GLOBAL

  • ポンプ水車

    三戸 良介, 宮川 和芳

    Patent

    J-GLOBAL

  • 羽根車

    宮川 和芳, 辻 浩二

    Patent

    J-GLOBAL

  • 水 車

    宮川 和芳, 難波 輝晃

    Patent

    J-GLOBAL

  • 水車および水車の補助羽根車の負荷分担率の決定方法

    特許第3392732号

    浅井 靖史, 佐橋 幹雄, 難波 輝晃, 前川 真丈, 宮川 和芳

    Patent

    J-GLOBAL

  • 羽根車およびターボ形ポンプ

    宮川 和芳, 大久保 剛

    Patent

    J-GLOBAL

  • フランシス水車

    前川 真丈, 宮川 和芳, 福田 暢英

    Patent

    J-GLOBAL

  • ポンプ取水装置

    前川 真丈, 宮川 和芳, 安田 俊雄, 清田 研治, 川村 昌生

    Patent

    J-GLOBAL

  • ポンプ

    特許第3310822号

    青木 聡明, 宮川 和芳

    Patent

    J-GLOBAL

  • シール装置及びそれを備えた水車

    川口 昭博, 小澤 豊, 篠原 種宏, 榊原 積徳, 宮川 和芳, 岩崎 純弘

    Patent

    J-GLOBAL

  • 補助羽根車付水車の羽根車形状

    佐橋 幹雄, 淺井 靖史, 難波 輝晃, 宮川 和芳, 前川 真丈

    Patent

    J-GLOBAL

  • 補助羽根車付水車又はポンプ水車

    佐橋 幹雄, 淺井 靖史, 難波 輝晃, 宮川 和芳, 前川 真丈

    Patent

    J-GLOBAL

  • ポンプ水車の羽根車

    岩崎 純弘, 宮川 和芳

    Patent

    J-GLOBAL

  • ハイブリッド形風力タービン

    宮川 和芳, 上原 重和

    Patent

    J-GLOBAL

  • 実揚程実落差試験装置

    宮川 和芳, 辻 浩二

    Patent

    J-GLOBAL

  • 内燃式ポンプ

    山田 績, 稲田 満, 宮川 和芳, 中村 裕樹, 西田 啓之

    Patent

    J-GLOBAL

  • 熱輸送装置

    宮川 和芳

    Patent

    J-GLOBAL

  • 水車またはポンプ水車

    宮川 和芳, 福田 暢英

    Patent

    J-GLOBAL

▼display all

Awards

  • 技術賞

    2021.05   ターボ機械協会   広範囲な流量・落差で運転可能な新形水車の開発

  • 論文賞

    2021.05   ターボ機械協会   ターボチャージャタービンの脈動流下における非定常内部流れと損失メカニズム

  • 技術賞

    2018.05   ターボ機械協会   熱効率50%のガソリンエンジン、ディーゼルエンジンを支える高性能ターボチャージャの開発

  • 技術賞

    2014.05   ターボ機械協会   中小水力発電所向け低コスト、高効率シュラウドレスフランシス水車の開発

  • 論文賞

    2009.05   ターボ機械協会   回転しながら軸方向に振動する円盤と静止円盤の間の半径方向隙間流れの動特性

  • 技術賞

    2005.05   ターボ機械協会   低騒音大容量軸流ポンプの開発

  • 論文賞

    2001.05   ターボ機械協会   フランシス水車の性能に及ぼすランナスプリッタブレードの効果

▼display all

Research Projects

  • 自動車用ターボチャージャの脈動流下における損失発生機構の解明

    日本学術振興会  科学研究費助成事業 基盤研究(C)

    Project Year :

    2019.04
    -
    2022.03
     

    宮川 和芳, 中村 揚平

     View Summary

    ターボチャージャは、自動車の排気量低減のために近年多用されているが、エンジンの排気脈動流下で運転されるため、非定常的な挙動を示し、定常流下と異なる性能であることが明らかになってきた。特に脈動流下の効率は定常流下に比べ低下することが確認されている。本研究ではターボチャージャのタービン、コンプレッサの脈動流による非定常的な挙動を流動解析および実験により明らかにする。2019年度は、タービン、コンプレッサの脈動流下での挙動を明らかにするために、ターボチャージャ試験装置を用いタービン、コンプレッサのそれぞれの性能を評価した。また非定常流動解析により、実験を補間した。
    タービンは脈動流下で大きな損失を発生し、特に、ホイール、下流ディフューザにおける損失が定常流下と比較して大きいことがわかった。タービンの出口流れは、最高効率点で無旋回に近いフローパーターンとなるように設計されるが、脈動流による体積流量の増減により絶対系において順旋回と逆旋回が交互に現れる。この旋回流れの特徴は流動解析とPIVによる流れの可視化により確認され、脈動流下の旋回流は準定常の同じ体積流量とは全く異なるフローパターンであり、また、増減によるヒステリシスも確認された。
    コンプレッサにおいては、脈動流下での流量、圧力の特性において大きなリサージュが確認され、タービンと同様に効率低下が確認できた。コンプレッサの運転範囲の制限に重要な特性であるサージに関しては、特に有意な知見が得られた。定常流下よりも脈動流下のサージラインは低流量側に移動し、また、その挙動の内特にサージサイクルの周波数は、脈動流の周波数の整数倍もしくは整数で除した値に引き込まれていくことがわかった。定常流下でのサージに関しては、システムの容量系の大きさを変えて、周波数への影響を確認したところ、GreizerのBパラメータで予測が可能であることを確認した。

  • Elucidation of flutter / divergence characteristics of elastic deformation propeller considering cavitation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2018.04
    -
    2021.03
     

Presentations

  • ギアポンプのキャビテーションエロージョン発生メカニズムと進行速度の予測

    Presentation date: 2009.03

  • 高温流体下でのポンプ吸い込み性能特性

    Presentation date: 2009.03

  • ポンプ水車ドラフトチューブキャビテーションロープのふれ回り挙動予測と抑制手法

    Presentation date: 2009.03

  • 流体機械研究のパラダイムシフトはできるか?

    Presentation date: 2008.05

  • バランスディスク隙間流れの動特性解析

    Presentation date: 2007.10

  • CFDによるターボ機械流体関連振動問題の解明

    Presentation date: 2006.11

  • バランスディスク隙間流れの動特性解析

    Presentation date: 2006.03

  • 高温給水系に用いられるポンプのキャビテーション特性

    Presentation date: 2005.09

  • 極低温流体用キャビテーション実験装置の製作

    Presentation date: 2005.05

  • 回流水槽向け低騒音ポンプの開発

    Presentation date: 2004.10

  • 斜流ポンプの動特性に関する実験的研究

    Presentation date: 2004.09

  • 羽根車形状の変更を伴った遠心ポンプ内部流れの数値解析

    Presentation date: 2004.09

  • 高性能液酸ターボポンプの開発

    Presentation date: 2004.05

  • ターボポンプインデューサの特性に関する研究

    Presentation date: 2004.05

  • ボイラ給水ポンプにおける羽根車後縁形状と右上がり特性

    Presentation date: 2004.05

  • ガイドベーン個別制御によるポンプ水車の性能向上

    Presentation date: 2003.08

  • ボリュートの影響を考慮した遠心ポンプ内部流れ数値解析

    Presentation date: 2003.08

  • Recent Research & Development Topics of Hydro-Turbomachinery

    Presentation date: 2003.06

  • 高落差ポンプ水車の軸スラストと隙間内流れ

    Presentation date: 2003.05

  • 入口フィンが遠心ポンプ不安定現象に及ぼす影響

    Presentation date: 2003.05

  • ポンプ水車ランナ取替による運転範囲の拡大

    Presentation date: 2003.04

  • 水力機械静止翼列の流体励振力と非定常応答(水車ステーベーンの振動発生メカニズム)

    Presentation date: 2002.11

  • 遠心ポンプにおける内部流れの数値解析

    Presentation date: 2002.09

  • フランシス水車のキャビテーション壊食に関する研究

    Presentation date: 2002.05

  • 斜流ポンプ右上がり特性域に関する実験的研究

    Presentation date: 2002.03

  • ポンプ水車ドラフトチューブ内部流れの非定常シミュレーション

    Presentation date: 2002.03

  • ポンプ取水槽水中渦予測法の研究

    Presentation date: 2001.11

  • 斜流ポンプにおける不安定現象の数値解析

    Presentation date: 2001.10

  • ポンプ取水槽の流れ解析による渦予測

    Presentation date: 2001.10

  • スプリッタ付きポンプ水車ランナの比速度別性能評価

    Presentation date: 2001.10

  • 三次元翼設計による遠心ポンプの性能向上

    Presentation date: 2001.05

  • ランナ改修による水車の性能向上-大橋発電所ランナ取り替え工事

    Presentation date: 2001.05

  • インデューサに生じる高次のキャビテーションサージとこれに伴う応力変動

    Presentation date: 2000.09

  • スプリッタ付き超高落差ポンプ水車ランナの振動強度評価

    Presentation date: 2000.08

  • ウォータージェットポンプ低流量域における不安定特性の改善に関する研究

    Presentation date: 2000.07

  • スプリッタ付きポンプ水車ランナの信頼性評価

    Presentation date: 2000.07

  • 三次元翼設計技術によるフランシス水車の効率向上

    Presentation date: 2000.05

  • 水車ドラフトチューブの内部流れの研究

    Presentation date: 1999.11

  • 遠心ポンプディフューザ内の二次流れ

    Presentation date: 1999.10

  • フランシス水車の翼列干渉効果

    Presentation date: 1999.10

  • エネルギ貯蔵システム技術の現状と将来の見通し(揚水発電技術)

    Presentation date: 1999.07

  • 遠心ポンプインペラの内部流れ

    Presentation date: 1999.07

  • 揚水発電技術の現状と将来の見通し

    Presentation date: 1999.07

  • スプリッタブレード付高落差ポンプ水車の開発

    Presentation date: 1999.07

  • スプリッタブレード付ポンプ水車の性能評価

    Presentation date: 1999.05

  • 水力機械の内部流れのCGによる可視化

    Presentation date: 1999.04

  • フランシス水車ランナの内部流れ(損失発生メカニズムの検討)

    Presentation date: 1998.10

  • フランシス水車ランナの内部流れ(ランナ内流れの粘性効果)

    Presentation date: 1998.08

  • 長寿命インデューサの開発

    Presentation date: 1998.04

  • 補助羽根車付新型水車の開発

    Presentation date: 1998.03

  • インデューサの長寿命化に関する研究

    Presentation date: 1998.03

  • 補助羽根車水車のキャビテーションに関する研究

    Presentation date: 1997.11

  • 補助羽根車付新型水車の開発

    Presentation date: 1997.11

  • 微少重力下のポンプの気泡除去技術

    Presentation date: 1997.11

  • 高落差・大容量のデリア形ポンプ水車を用いた可変速揚水発電システム

    Presentation date: 1997.10

  • 高落差大容量可変速デリア形ポンプ水車の開発

    Presentation date: 1997.05

  • 気泡除去要素技術開発

    Presentation date: 1997.04

  • CFDを用いたフランシス水車二重円形翼列の設計

    Presentation date: 1997.03

  • 斜流ポンプ低流量域の内部流れ

    Presentation date: 1996.11

  • 流れのディストーションによるターボ機械翼列の非定常応答

    Presentation date: 1994.11

  • 非圧縮三次元粘性流動解析によるターボ機械詳細流れの把握

    Presentation date: 1994.05

  • 大きな変動落差幅を有するポンプ水車の開発

    Presentation date: 1994.05

  • 数値解析技術を用いた最近のハイドロタービン設計

    Presentation date: 1993.11

  • 三次元粘性流動解析による水力機械の流れ

    Presentation date: 1991.03

  • 非定常静・動翼列干渉流れの数値計算とその動画化

    Presentation date: 1990.12

  • 水車平行型スピードリング内流れの実験的研究

    Presentation date: 1989.05

  • 風力発電システムに関する研究(第14報、風力タービンシステムの運転制御(2))

    Presentation date: 1985.06

  • 風力発電システムに関する研究(第13報、風力タービンシステムの運転制御(1))

    Presentation date: 1985.06

▼display all

Specific Research

  • 低密度極低温ターボポンプの効率、キャビテーション性能向上に関する最適設計手法の研究

    2011  

     View Summary

    1.背景 液体水素、LNG等の輸送に使われる極低温用ポンプに関して、今後、ロケット向け再利用型ターボポンプや液体水素供給用ポンプ、環境負荷低減のための高効率LNGポンプなどの開発が予定されている。これらの種類のポンプについては、従来より産業用ポンプの開発研究成果の横通しが実施され実用化されてはいるが、前述の用途ではさらなる効率、信頼性の向上、運用範囲の拡大が求められる。特に、液体密度の小さな液体向けターボポンプに関しては、羽根車の設計形状も流体密度の大きな産業用ポンプ、流体密度の小さな遠心圧縮機の両方の特徴が混在していて、効率、キャビテーション等の流体性能向上のための最適化手法が十分研究されてはいなく、内部流れの精査による性能改善の余地が残っている。本研究では、従来研究提案者が実施してきた遠心羽根車の内部流れ、キャビテーション性能改善の研究成果をベースに特に流体密度の小さな極低温流体用ターボポンプ課題を解明し、今後開発されるポンプの最適設計コンセプトを構築、性能向上に資する。2.研究目的 低密度極低温用ターボポンプの設計点、非設計点での損失発生メカニズムの解明、キャビテーション性能の予測、およびそれらに基づく設計指針の構築3.研究結果3.1 低密度極低温向け(液体水素)ターボポンプの仕様、設計手法のベンチマーク従来の国内外の低密度極低温向けターボポンプとしてLE7、LE5、RL10A、J-2、J-2S、SSME等のロケットエンジン向け液体水素ターボポンプ他の寸法、形状、性能を調査し、設計手法、特徴等をまとめた。ベンチマークの結果、角運動量を決めるインペラ出口角等の最適化は検討の余地があり、以下仕様のJAXA液体水素ターボポンプに関して検討を進めることとなった。検討仕様(ポンプ形式:インデューサ付2段遠心ポンプ、回転数:42000rpm、流量34.3kg/s、比速度140rpm,m,m3/min、入口圧力0.34MPa、出口圧力26.7MPa、入口温度20.7K、インデューサ直径163.8mm、主羽根車直径238mm)ただし、本研究では、上記仕様のうちインペラの3.2 遠心羽根車、ディフューザ形状モデリング手法の構築 一次元性能予測、CFD等の検討に用いることができる三次元羽根車、ディフューザの形状モデリングプログラムを構築。子午面、翼角分布で得た特徴をコントロールすることができるようにパラメータ設定を実施した。3.3 羽根車設計パラメータの変化による内部流れ、損失メカニズム変化の定量的予測 要求仕様に合わせて羽根車を設計し、それらの負荷を変化させることにより羽根車の内部流れ、損失発生メカニズムの定量的変化を把握した。 翼出口角を大きくすることにより高負荷化で下流ディフューザの損失が増加する。性能向上のためのポンプの反動度、負荷分担を明確にした。予測には、一次元損失モデルをベースとしたプログラムを作成し性能評価に用いた。3.4 CFDを用いた羽根車、ディフューザの最適代表寸法、三次元設計形状の検討 汎用CFDコードを用い一次元性能評価結果をベースに設計した羽根車、ディフューザのさらに詳しい内部流れを把握した。また、内部流れの評価により代表寸法の最適化を図った。3.5 低密度極低温流体向けポンプ羽根車、ディフューザの最適設計手法まとめ 圧縮機、水用ポンプ羽根車との比較をベースに、低密度極低温流体用ターボポンプの設計手法をまとめ、最適設計結果のポンプ形状に関しては、効率、キャビテーション性能を設計点、非設計点で予測し、設計データベースとして整理する。また、流体密度に関しての設計手法もまとめる。4.成果 従来の極低温用ポンプは、信頼性の確保を最重要プライオリティとして設計されてきたが、本研究では、低密度流体向け羽根車の流体性能、設計手法を検討し、さらなる効率、キャビテーション性能の向上を検討した。空気機械と水力機械の中有間的特徴を有する低密度流体向けポンプの研究は、流体密度に関して設計手法の横通しを図るものであり、新しいトレードオフの実施方法、形状決定プロセス等が設計指針の他成果として残り、今後の流体機械開発に有用である。

 

Syllabus

▼display all

 

Committee Memberships

  • 2022.04
    -
    Now

    The Japan Society of Mechanical Engineers  Kanto Branch, Tokyo Block Chair

  • 2022.04
    -
    Now

    The Japan Society of Mechanical Engineers  Fluids Engineering Division Chair

  • 2020.05
    -
    Now

    Turbomachinery Society of Japan  Vice Chair

  • 2022.09
    -
    2024.09

    電気学会「水車およびポンプ水車の寸法検査標準」標準特別委員会  「水車およびポンプ水車の寸法検査標準」標準特別委員会 委員

  • 2021.04
    -
    2022.03

    The Japan Society of Mechanical Engineers  Kanto Bramch Tokyo Block Vice Chair

  • 2021.04
    -
    2022.03

    The Japan Society of Mechanical Engineers  Fluids Engineering Division Vice Chair

  • 2020.04
    -
    2021.03

    The Japan Society of Mechanical Engineers  Fluids Engineerring Division Secretary

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