研究者詳細 - 李　洛中

李　洛中 (リ　ナクジュン)

写真a

所属	理工学術院基幹理工学部
職名	講師（任期付）

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Performance of counter-rotating tandem propellers at oblique flow conditions

Nak Joong Lee, Morihito Inagaki, Toshiaki Kanemoto

IOP Conference Series: Earth and Environmental Science 240 ( 5 ) 2019年03月 [査読有り]

　概要を見る

© Published under licence by IOP Publishing Ltd. Tidal currents are a potential source of reliable and renewable energy. Various power generation systems have been proposed. The authors developed a counter-rotating type tidal stream power unit in which the tandem runners make the inner and the outer armatures counter-rotate. The unit is composed of tandem propellers with 3 front and 5 rear blades and has a promising advantage that the rotational torque between the front runner and the rear propellers, namely the inner and the outer armatures, is balanced in the unit. That is, this tidal stream power unit can be moored with only one cable and then its nose and tail will naturally line up in response to the tidal stream by yawing. In this paper, the performance of the propellers in oblique flow conditions were investigated experimentally and numerically. When the coming flow obliquely to the propeller by 30 degrees, the performance deteriorates by 20%.

DOI
Performance of tandem propellers counter-rotating obliquely to tidal stream

Nak Joong Lee, Toshiaki Kanemoto, Kazuo Kuwano, Isao Samura

Proceedings of the International Offshore and Polar Engineering Conference 253 - 256 2017年 [査読有り]

　概要を見る

Copyright © 2017 by the International Society of Offshore and Polar Engineers (ISOPE). The authors have developed a counter-rotating type hydroelectric unit where tandem runners counter-rotate inner and outer armatures in a peculiar generator, and the unit has penetrated into the market in the small/micro hydropower. The unit has promising advantages such as the rotational torque is counter-balanced itself between the front and the rear runners, namely the inner and the outer armatures. Such technology has been provided for the tidal power unit moored to the seabed with one cable. Tidal stream is abundant and clean energy resource whose power is predictable and sustainable. To generate power effectively from the stream, the unit must effectively work in response to change of the flow direction not only in day cycle but also in unsteady condition with turbulent fluctuation. This paper discusses the effects of the flow direction on the output of the tandem propellers by commercial Computational Fluid Dynamics (CFD) code.
Experiments on the magnetic coupling in a small scale counter rotating marine current turbine

I. C. Kim, N. J. Lee, J. Wata, B. S. Hyun, Y. H. Lee

IOP Conference Series: Materials Science and Engineering 129 ( 1 ) 2016年05月 [査読有り]

　概要を見る

Modern economies are dependent on energy consumption to ensure growth or sustainable development. Renewable energy sources provide a source of energy that can provide energy security and is renewable. Tidal energy is more predictable than other sources or renewable energy like the sun or wind. Horizontal axis marine current turbines are currently the most advanced and commercially feasible option for tidal current convertors. A dual rotor turbine is theoretically able to produce more power than a single rotor turbine at the same fluid velocity. Previous experiments for a counter rotating dual rotor horizontal axis marine current turbine used a mechanical oil seal coupling that caused mechanical losses when water entered through small gaps at the shaft. A new magnetic coupling assembly eliminates the need for a shaft to connect physically with the internal mechanisms and is water tight. This reduces mechanical losses in the system and the effect on the dual rotor performance is presented in this paper.

DOI
Performance investigation of a counter-rotating tidal current turbine by CFD and model experimentation

Nak Joong Lee, In Chul Kim, Beom Soo Hyun, Young Ho Lee

Journal of Mechanical Science and Technology 30 ( 2 ) 519 - 524 2016年02月 [査読有り]

　概要を見る

© 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg. Global warming is one of the issues in the world, which is mainly due to the burning of fossil fuels. Thus, alternative energy is now paramount in the 21st century. In Korea, the tidal currents in the southwestern sea have a wide range of currents that are available for tidal current power generation. Single rotor turbines can obtain a theoretical maximum power coefficient of 59.3%, whereas dual rotor turbines can attain a maximum of 64%. In this study, the performance and efficiency of a counter-rotating tidal current turbine is investigated when changing the front and rear blade angles at different water velocities. The investigation was conducted by using Computational fluid dynamics (CFD) and experimental methods highlighted in this study. When varying these parameters, changes in the streamlines were observed in the CFD results. The changes in flow stability over the blade surfaces observed in the numerical results were reflected in the power and power coefficient graphs presented in this study. The results obtained by the experiments were also shown to be in good agreement with the CFD results.

DOI
Counter-rotating turbine in unique power unit provided for bidirectional tidal streams

Toshiaki Kanemoto, Nak Joong Lee, Man Woong Heo, Bin Huang, Yuji Nakanishi, Yuki Funami

Proceedings of the 12th ISOPE Pacific-Asia Offshore Mechanics Symposium, PACOMS 2016 254 - 258 2016年 [査読有り]

　概要を見る

Copyright © 2016 by the International Society of Offshore and Polar Engineers. The energy from a tidal stream is abundant and renewable resource whose power is predictable and sustainable. To generate power effectively from the stream a unique counter rotating type tidal stream power unit, whose tandem rotors drive inner and outer armatures in a generator, has been provided by the authors. At the tidal power station located in narrow straits, the unit needs to be reoriented so that useful output power can be obtained from both flood and ebbing tides. In this paper, the counter rotating tandem rotor turbine was designed for operation in a bidirectional tidal stream and the performance was analyzed. The maximum output power is somewhat lower than that of the rotors designed exclusively for a unidirectional stream. The relative flow has a positive angle of attack at the leading edge and discharges from the trailing edge along the blade camber. The angular momentum change, namely the rotor work, is seen to always be accompanied with a shock loss at the leading edge.