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고받음각에서 프렁잉(Plunging) 진동하는 날개 주위의 아음속 유동해석
이경환(K.H. Lee),김재수(J.S. Kim),전승배(S.B. Jun) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
Many numerical and experimental researches have been done for the flow around oscillating airfoils. The main research topics are wake vortex shading, dynamic stall phenomenon, MAVs lift and thrust generation, et.al. Until now, researches mainly have been concentrated to analyze the wake flow for the variation of frequency and amplitude at a low angle of attack. In this study, wake structures and acoustic wave propagation characteristics were studied for pure harmonic plunging oscillating airfoil at a high angle of attack. The governing equations are the Navier-Stokes equation with LES turbulence model. OHOC (Optimized High-Order Compact) scheme and 4th order Runge-Kutta methods were used. The Mach number is 0.3,the Reynolds number is 1.0×10<SUP>5</SUP>,and the angle of attacks are 20° ~ 50°. The plunging frequency and the amplitude are from 0.05 to 0.15, and 0.1?0.2, respectively. Because of the high resolution numerical methods, wake vortex shedding and pressure wave propagation process, as well as the propagation characteristics of acoustic waves can be simulated. The results of frequency analysis show that the flow has the mixed characteristics of the forced plunging frequency and the nature vortex shedding frequency at a higt angle of attack.
이경환(G. H. Lee),심규진(K. J. Shim),이용훈(Y. H. Lee),정한식(H. S. Chung),정효민(H. M. Jeong) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The study about hydrogen fuel which consist of hydrogen extraction and reforming process, fuel cell equipment, and receptacle are flourishing all over the world. Currently, Korean hydrogen station is still underdeveloping. And also the most important part which is hydrogen compressor has not been developed. Snubber is one of the most important parts inhydrogen compressing system. It has installed reciprocating hydrogen compressor. One of these components is snubber which has function to reduce pulsation waveform and to remove the impurities in the hydrogen gas. Therefore, a snubber has a buffer. It is an inclined plate, attached inside snubber. The best snubber is the one which has the least pressure loss and the most pressure amplitude reduction. Furthermore, investigating geometric optimum size of with-buffer snubber has been done by numerical analysis approach.