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신필권(Phil-Kwon Shin),박종호(Jong-Ho Park) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.8
??초음속 흡입구 buzz는 입구에서의 충격파 패턴의 진동과 내부압력요동을 동반하는 불안정한 아임계 직동으로 정의할 수 있다. 이러한 유동섭동은 연소실 실화나 엔진의 구조적 손상을 일으킬 수 있다. 축대칭, 외부 압축형 흡입구에서 초음속 흡입구의 buzz현상을 조사하기위한 실험적 연구가 수행되었다. 자유류 마하수 2.0에서 카울 입구 직경이 30㎜ 인 흡입구 모델이 시험되었다. 아임계 불안정성은 압력섭동의 주파수 및 입구에서의 충격 파 구조 분석을 통해 조사되었다. 실험결과 전압력 회복비는 0.42에서 0.78까지, 포획 면적비는 0.34에서 0.98까지 변화했다. 아임계 유동의 주파수는 포획 면적비 감소에 따라 증가했으며 주파수는 범위는 224~240㎐ 였다. Supersonic inlet buzz can be defined as unstable subcritical operation associated with fluctuating internal pressures and a shock pattern oscillating about the inlet entrance. The flow pulsations could result in flameout in the combustor or even structural damage to the engine. An experimental study was conducted to investigate the phenomenon of supersonic inlet buzz on axisymmetric, external-compression inlet. An inlet model with a cowl lip diameter of 30㎜ was tested at a free stream Mach number of 2.0. Subcritical instability was investigated by considering the frequency of pressure pulsation and shock wave structure at the inlet entrance. The results obtained show that total pressure recovery ratios were varied from 0.42 to 0.78, and capture area ratio from 0.34 to 0.98. The frequency of the subcritical flow increased with decrease in capture area ratios. Frequency was measured at 224 ~ 240㎐.
신필권(Phil-Kwon Shin),박종호(Jong-Ho Park),이용범(Yong-Bum Lee) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.3
축대칭 외부압축식 초음속 흡입구의 버즈 억제방법을 조사하기위해 마하 2.0 유동에서 실험적 연구를 수행하였다. 흡입구 모델은 고정형이고 내부 수축부는 없으며, 형상변화는 엔진덮개의 교체에 의해 이루어진다. 실험결과 버즈의 원인은 충격파 교차점에서 발생하는 와류면을 경계로 형성되는 불연속 유동장과 관련이 있는 것으로 나타났다. 외부압축식 흡입구에서는 경사충격파를 카울 앞이나 뒤에 위치하게 함으로써 buzz를 억제할 수 있다. An experimental study was conducted at a Mach number of 2.0 to investigate the buzz suppression method on an axisymmetric, external compression supersonic inlet. The inlet model has a fixed geometry with no internal contraction. The inlet configuration was altered by changing the cowling. Results show that source of buzz has been related to the existence in the flow field of velocity discontinuity across a vortex sheet which originates from a shock intersection point. With external compression inlet, buzz can be suppressed by positioning the oblique shock slightly inside or outside of the cowl.
문덕수 ( Deok Soo Moon ),김현주 ( Hyun Ju Kim ),신필권 ( Phil Kwon Shin ),정동호 ( Dong Ho Jung ) 한국수산과학회 2005 한국수산과학회지 Vol.38 No.1
N/A We have developed a new method of manufacturing salts by horizontal spray drying technique, using the concentrated deep ocean water after desalination processes. We studied the chemical characteristics of the spray-dried salts. Sodium content in the spray salts is 28.4%, which is 10-30% lower than that of bay salts, bamboo salts and boiling salts (32-38.2%). However, the contents of magnesium, potassium and calcium of the spray salts are 2.5 times, 3 times and 4.5 times higher relative to those of bay salts, respectively. On the one hand, sulfur content in spray salts is 14 times lower than those of bay salts, which is caused by their volatilization during spray and vaporization of the concentrated seawater. Enrichment factors of Mg (0.8), K (0.9) and Ca (1.0) in the spray salts are relatively higher than those in bay salt (0.2-0.3), bamboo salt (0.15-0.4) and boiled salt (0.4-0.7), respectively. On the contrary, enrichment factor of sulfur in spray salts is observed to be 0.07, which is considerably lower than those in other salts (0.3-0.7). It means that the minerals like Mg, K and Ca can be well conserved from seawater to salts through spray drying techniques, while volatile elements like sulfur, lead, mercury and organic compounds can be easily removed from seawater via spray and heating processes.
수평형 고자기장 초전도 자석용 크라이오스텟의 지지구조물 하중 완화 방법
이병섭(Byoung-Seob Lee),김동락(Dong-Lak Kim),최연석(Yeon Suk Choi),양형석(HyungSuk Yang),신필권(Phil Kwon Shin) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The study related on support system of cryostat for 21 T horizontal type superconducting magnet is presented. Especially, the deformation behavior of cryostat under magnetic field and thermal contractions at cryogenic temperatures is dealt with the analytical method related on Finite Element Analysis. From the results, we know that the strain by self weight and thermal contraction contribute to serious damage. Also, we will introduce about weight relief design for the structural integrity of support system.