• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.74-77
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• 2011

고성능 다단연소방식 액체 로켓엔진에 사용되는 기체 중심 스월 동축형 분사기의 리세스 길이 변화에 따른 혼합특성을 수치해석을 통해 연구를 수행하였다. 실제 추진제의 상(phase)은 기체(산화제)-액체(연료)형이지만, 모사조건을 통해 기체-기체로 고려하였다. 추진제의 확산각도를 측정하기 위해 분사기 출구에서의 속도 분포 및 추진제의 분무형상을 분석하였다. 리세스 길이가 증가함에 따라 축방향 속도는 증가하는 반면, 탄젠셜 방향 속도는 감소하였다. 이 결과 확산각도가 감소하는 정성적인 특징을 확인하였다.

• 한국분무공학회지
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• 제19권4호
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• pp.167-173
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• 2014

The spray characteristics of Gas-Centered Swirl Coaxial Injector was investigated that there were different characteristics with or without gas flow. As gas flow was accelerated, the momentum of gas was transferred to the momentum of liquid in the low liquid Reynolds number. Therefore, the axial velocity of liquid was increased and the measured value was smaller than without gas flow. However, in the high momentum flux ratio, the momentum transfer hardly occurred and the results had constant values. As the recess length was increased, the mixing area of gas and liquid also was increased, the results were decreased.

• 한국분무공학회지
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• 제20권3호
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• pp.168-174
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• 2015

Combustion instability is critical problem in developing liquid rocket engine. There have been many efforts to solve this problem. In this study, the method was sought through the injector as part of these efforts to suppress combustion instability. If the injector can suppress the disturbance coming from the supply line as a kind of buffer it will serve to reduce combustion instability. Especially we target at gas propellant oscillation in gas-centered swirl coaxial injector. The phenomenon is simulated with acoustic excitation of speaker. The film thickness response at injector exit was measured by using a liquid film electrode. Also the response of spray to the disturbance was observed by high-speed photography. Gas-liquid momentum flux ratio and the frequency of feeding gas oscillation were changed to investigate the effect of these experimental parameters. The trend of response by varying these parameters and the cause of weak points was studied to suggest the better design of injector for suppressing combustion instability.

• 한국추진공학회지
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• 제24권4호
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• pp.25-32
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• 2020

모형 연소기에서 동축형 분사기에 의한 연소불안정성을 운동량비 변화에 따라 수치적으로 분석하였다. 실제 로켓 엔진의 경계조건을 기반으로 총 5개의 운동량비를 선택하였다. 운동량비가 증가할수록 분사기 출구에서의 확산각도는 감소하는 경향을 보였으며, 축방향 운동량이 증가할수록 연소기 내부의 압력진폭이 크게 감소함을 확인하였다. 동적 모드 분해 기법(dynamic mode decomposition)을 통해 연소기내의 음향 모드를 파악하였고 관심 섭동 주파수를 갖는 2L 모드(mode)의 감쇠계수를 구하고 이를 통해 운동량비가 증가할수록 연소기의 안정성이 증가함을 보였다.

• 한국분무공학회지
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• 제22권2호
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• pp.62-68
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• 2017

It is important to study on the combustion instability to develop liquid rocket engines for preventing lower combustion efficiency and destruction of combustion chamber. There are many researches on simplex injector with liquid pulsation to solve this problem. In real rocket engine system, however, they use coaxial injectors. Therefore, research on coaxial injector with liquid pulsation is essential. In this study, we investigate dynamic characteristics of gas centered swirl coaxial injector varying tangential inlet diameter. A mechanical pulsator was used to generate an excitation in the liquid flow, and the response characteristics of the injector were confirmed. As tangential inlet diameter increased, mass flow rates increased and spray angle decreased. As tangential inlet diamter decreased, gain decreased because the pressure fluctuation in the injector manifold rarely passed through the inlet. Additionally, it was confirmed that a sufficiently small tangential inlet served as a damper.