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터보펌프 인듀서의 흡입성능에 대한 직경과 회전속도의 영향
손동기(Dong Kee Sohn),구현철(Hyun Chul Koo),차봉준(Bong Jun Cha),양수석(Soo Seok Yang),이대성(Dae Sung Lee) 한국유체기계학회 2001 유체기계 연구개발 발표회 논문집 Vol.- No.-
The turbopump inducer cavitation is very important for the success of a liquid rocket engine. In this study the performance test and cavitation performance test were carried out at various rotational speed with two different diameter inducers. The rotational speed were varied 4000, 6000, 8000 rpm and the variation to the diameter of an inducer were taken as design size and 2 times enlarged size.<br/> The major results of the present study were as follows.<br/> 1. The hydraulic performance results showed that the similarity was met over the entire test range of the present study.<br/> 2. The blade thickness effect was examined and showed that the increased blade thickness resulted in decreased efficiency and worse cavitation performance for large tip clearance.<br/> 3. The cavitation performance test results showed that the breakdown NPSH increases as the flow coefficient and does not affected by the rotational speed.
주유동의 맥동과 엇갈린 2열 분사홀로부터의 막냉각 : 분사비의 영향
손동기,이준식,Sohn, Dong Kee,Lee, Joon Sik 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.9
Periodic pulsations in the static pressure near turbine surfaces as blade rows move relative to each other is one of the important sources of turbine unsteadiness. The present experiment aims to investigate the effect of the static pressure pulsations on the interaction of film coolant flows from two rows of staggered holes with mainstream and its effect on film cooling heat transfer. Potential flow pulsations are generated by the rotating shutter mechanism installed downstream of the test section, The free-stream Strouhal number based on the boundary layer thickness is in the range of 0.033 - 0.33, and the amplitude of about 10-20%. Measured are time-averaged and phase-averaged velocity variations, pressure variations and temperature distributions of the flow field. Experimental conditions are identified by boundary layer measurements. Injectant behavior is characterized by the measurements of unsteady pressure in the plenum chamber and free-stream static pressure. The film cooling effectiveness is evaluated from the insulated wall temperature measurement. It has been found that bulk flow pulsation provides very large diffusion of the injectants and the effectiveness is significantly reduced by the flow pulsations.
원형 제트 충돌 열전달과 유동 특성에 관한 실험적 연구 : 노즐 벽 두께와 노즐 출구 압력의 영향
윤상헌,양근영,손동기,최만수,Yoon, Sangheon,Yang, Geunyoung,Sohn, Dong Kee,Choi, Mansoo 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.10
An experimental study on heat transfer and flow characteristics of a circular impinging jet on a flat plate has been carried out. Of particular interests are the effects of nozzle wall thickness and nozzle exit pressure. Experimental apparatus has been designed to view heating plate coated by TLC from the opposite side of the nozzle in order to measure heat transfer rates for cases of very small nozzle to plate spacings. A visualization study of jet flows has also been performed. As the nozzle wall thickness increases at small nozzle to plate spacings, the effect of mixing is inhibited due to the confinement caused by the finite nozzle wall, consequently, heat transfer rates have been decreased. At small nozzle to plate spacings, heat transfer rates and nozzle exit pressures are increased together, therefore, enhancement of heat transfer at small nozzle to plate spacings should be considered in conjunction with the need of more fan power to generate the same Reynolds numbers.