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횡단 유동장으로 펄스 분사된 액체 제트의 분무 구조 및 단면 분포 특성
이인철(Inchul Lee),구자예(Jaye Koo) 한국추진공학회 2009 한국추진공학회지 Vol.13 No.2
Present studies of these experiments was conducted to using water, over a range of cross-flow velocities from 42 to 136 m/s, with injection frequencies from 35.7 to 166.2 Hz. In cross-flow field, main parameters of liquid jet for secondary breakup were cross-flow drag rather than pressure pulse frequency. As oscillation of the periodic pressure, liquid jet was moved up and down. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. Because of pressure pulsation frequency, an inclination of SMD for the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. The tendency of volume flux value for various frequency of pressure pulse was same distribution. And volume flux was decreased when the frequency of pressure pulse increasing.
파이로 시동기의 압력변화와 터빈 블레이드 회전수 변화에 따른 충동형 터빈 블레이드 입구의 가스온도 분포 해석
이인철(Inchul Lee),변용우(Yongwoo Byun),구자예(Jaye Koo),이상도(Sangdo Lee),김귀순(Kuisoon Kim),문인상(Insang Moon),이수용(Sooyoung Lee) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11
부분 흡입형 터빈의 표면 가스온도 분포 해석은 유동장 내부가 3차원의 매우 복잡한 유동장을 구성하기 때문에 실제 해석상 많은 시간이 소요된다. 파이로 시동기는 입사각 18°로 설치되어 있으며, 105개의 충동형 터빈 블레이드로 구성되어 있다. 다양한 파이로 시동기 압력 변화에 대하여 터빈 블레이드의 표면 가스온도 분포 해석이 이루어 졌으며, Round형의 터빈 블레이드는 1423K의 온도와 7.2MPa의 압력 조건에서 16000rpm까지 회전하게 된다. 파이로 시동기의 압력과 터빈 블레이드의 회전수가 증가함에 따라 터빈 블레이드의 표면 가스 온도는 하강하게 되며, 파이로 시동기 압력이 5.75MPa 이고 회전수가 12100rpm의 보다 증가함에 따라 터빈 블레이드로 입구의 유동장에는 균일한 표면 가스 온도가 유입되는 것을 확인 할 수 있었다. As the partial admission turbine has a intrinsically unsteady and three dimensional flow region, numerical calculation time of these study has been too long time. The numerical analysis for gas temperature of turbine blade surface has been performed to investigate development of temperature with various pyro start pressure. Computations have been carried out several turbine rotational speeds in the range from 0 to 16000 rpm and inlet conditions with 1423K, 7.2MPa. As a result, the more rotational speed and pyro starter pressure of turbine increased, the more turbine blade"s temperature decreased. It is also found that flow field of turbine blade inlet area at pyro starter pressure of 5.75MPa and rotational speed of 12100 rpm formed surface temperature uniformly.
초고속 발사체의 액체 저장부 충돌에 의한 초음속 액체 제트의 분무 속도 및 분열 특성
이인철(Inchul Lee),신정환(Jeunghwan Shin),김희동(Heuydong Kim),구자예(Jaye Koo) 한국가시화정보학회 2011 한국가시화정보학회지 Vol.9 No.1
Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 ㎬. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.
2중 유로형 전단 동축 분사기의 기체 분사율에 따른 유동 및 입도분포
이인철(Inchul Lee),김도헌(Dohun Kim),구자예(Jaye Koo) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.7
전단 동축 분사기의 Inner-stage와 Outer-stage의 기체 분사 비율 변화에 따른 축방향 유동 분포특성과 분무 분열 특성을 실험적으로 연구였다. 무차원 측정 거리를 Z/d=100까지 변화시킴에 따라 운동량 교환, 공기역학적 항력, 점성 혼합의 영향으로 완전 발달된 유동의 형태를 나타내었다. Inner-stage의 기체분사와 Outer-stage의 기체 분사의 영향은 Z/d=5 이내의 영역에서 간섭받지 않고 분무초기에 Inner-stage에서 분사된 기체 전단력에 의해 분열됨을 파악할 수 있었으며, Z/d=10 이상의 영역에서 완전 발달된 유동으로 변화하며, 유동의 혼합이 진행됨을 관찰 할 수 있었다. Inner-stage의 운동량 플럭스 비 0.84 이내에서 Outer-stage의 운동량 플럭스 비가 증가함에 따라 SMD가 감소하는 경향을 나타내었으며, Inner-stage의 운동량 플럭스 비가 1.38 이상의 조건에서 SMD의 분포가 유사하게 나타나는 경향을 관찰할 수 있었다. To verify the effect of inner- and outer-stage gas jets, a shear coaxial injector was designed to analyze the axial velocity profile and breakup phenomenon with an increase in the measurement distance. When the measurement position was increased to Z/d=100, the axial flow showed a fully developed shape due to the momentum transfer, aerodynamic drag effect, and viscous mixing. An inner gas injection, which induces a higher momentum flux ratio near the nozzle, produces the greater shear force on atomization than an outer gas injection. Inner- and Outer-stage gas injection do not affect the mixing between the inner and outer gas flow below Z/d=5. The experiment results showed that the main effect of liquid jet breakup was governed by the gas jet of an inner stage. As the nozzle exit of the outer-stage was located far from the liquid column, shear force and turbulence breaking up of the liquid jets do not fully affect the liquid column. In the case of an inner-stage gas injection momentum flux ratio within 0.84, with the increase in the outer gas momentum flux ratio, the SMD decreases. However, at an inner-stage gas jet momentum flux ratio over 1.38, the SMD shows the similar distribution.
부분입사형 초음속 터빈의 블레이드 표면 온도에 블레이드 앞전 형상이 미치는 영향
이상도(Sangdo Lee),김귀순(Kuisoon Kim),이인철(Inchul Lee),구자예(Jayae Koo),문인상(Insang Mun),이수용(Suyoung Lee) 한국추진공학회 2008 한국추진공학회지 Vol.12 No.4
In this paper, numerical analysis of the surface gas temperature on turbine blades has been performed to investigate the temperature profiles characteristics of a partial admission supersonic turbine driven by high temperature and pressure gas of pyro-starter with two different types of turbine blade edge shape. In order to examine the surface gas temperature on turbine blades at initial starting, computations tlave been carried out at several turbine rotational speeds in the range of 0~10,000 rpm for each type of turbine edge shape. Sharp edge and Round edge types were taken as the turbine edge shape factor. As turbine rotational speed increased, the average temperature of turbine blades was further decreased. It was also found that the surface temperature of turbine blades with a sharp edge was lower than round-type edge turbine blades.