• 한국분무공학회지
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• 제22권4호
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• pp.159-168
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• 2017

Numerical studies on the spray characteristics of closed-type and open-type swirl injectors were conducted using ANSYS Fluent. By changing injection pressures, discharge coefficient and spray angle were calculated using the Reynolds stress BSL turbulent model. The numerical results were compared with previous experimental data to examine their accuracy. For a closed-type swirl injector, spray angles matched well with experimental results and discharge coefficients showed approximately 8% differences. On the contrary, discharge coefficients of an open-type swirl injector were similar with experimental result but its spray angles presented around 15% differences. Though the numerical results were not perfectly consistent with experimental data, it is thought that they could be sufficiently used for analyzing spray characteristics, specially which is hard to be measured from experiments. Numerical simulation with different turbulent models was also performed to examine their effects on the numerical results.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.131-136
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• 2003

Experimental study on combustion characteristics of double swirl coaxial injectors has been conducted for the assessment of critical design parameters of injectors. A subscale thrust chamber has been fabricated with a water-cooled copper nozzle, which allows a chamber to be reused without replacing parts. Two different designs of injectors have been tested for the understanding of the effects of recess length on combustion. Clearly, the recess length drastically affects the combustion efficiency and hydraulic characteristics of the injector. Internal mixing of propellants in the injector with the recess number of two increases a combustion efficiency and reveals sound combustion although a pressure drop required for the similar amount of mass flow rates increases compared with the injector of the recess number of one.

• 한국자동차공학회논문집
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• 제21권4호
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• pp.89-95
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• 2013

In this work, the evaluation of swirl nozzle injector performance was conducted by investigating effective area ($A_{eff}$), injection mass ($m_{inj}$), injection rate ($Q_{inj}$), and injection delay ($t_{delay}$) under various test conditions. To achieve these, fuel injection analysis system which was composed of fuel supply system, injection system, and control system was installed. At the same time, the swirl nozzle that had 12 orifice hole with $120^{\circ}$ injection angle was used in this work. It was revealed that the difference of injection mass ($m_{inj}$) between base and swirl nozzle injector increased as the injection pressure ($P_{inj}$) and energizing duration ($t_{eng}$) decreased under the same test conditions. The maximum injection rate ($Q_{inj}$) of swirl nozzle injector was higher than base nozzle injector about 2~5%. The injection performance of swirl nozzle was better than base nozzle at low injection pressure ($P_{inj}$) and short energizing duration ($t_{eng}$) conditions.

• 한국항공우주학회지
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• 제43권7호
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• pp.619-625
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• 2015

스월 인젝터는 액체로켓 엔진에서의 연료 분사 장치로 널리 사용되고 있으며, 이에 따른 연구 또한 활발하게 진행되고 있다. 특히 연소 불안정 문제를 해결하는 것은 모든 종류의 액체로켓 엔진에서 필수적이다. 본 연구에서는 연소불안정을 해결하기 위한 기초 연구로 오픈형 스월 인젝터에 대한 수류실험을 수행하였다. 인젝터로 유입되는 작동유체에 압력 섭동을 발생시키고, 그에 따른 응답특성을 실험적으로 파악하였다. 또한, 인젝터 스월 챔버의 길이와 지름을 변화시킴으로써 인젝터 구조의 변화에 따른 응답 특성의 변화를 확인하였다.

• 한국추진공학회지
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• 제20권4호
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• pp.68-76
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• 2016

본 연구는 이원추진제 추력기의 핵심부품에 대한 성능평가의 일환으로, 기체메탄/액체산소를 추진제로 사용하는 스월 동축형 인젝터의 리세스 길이 및 분사압력에 따른 분무특성 파악을 목표로 하였다. 분무형상은 슐리렌 가시화 기법을 이용하여 획득하였고, 슐리렌장치는 광원, 오목거울, 초고속카메라 등으로 구성된다. 내부 인젝터에 의한 액체 분무의 경우 hollow cone 형상을 확인하였으며, 내부 인젝터 오리피스 길이의 증가와 함께 스월강도 감쇠의 영향으로 분무각은 줄어들었다. 기체-액체를 함께 분사할 때, 분무각은 리세스 길이가 증가함에 따라 외부혼합영역에서 증가하지만, 내부혼합영역에서는 작아졌는데, 액체분무 분사 압력의 높고 낮음에 무관하다는 사실을 확인하였다.

• 한국분무공학회지
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• 제9권1호
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• pp.21-29
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• 2004

The flow characteristics of a swirl injector were investigated with the variation of the flow condition and geometric dimensions, such as orifice length for considering the viscous effect and tangential entry port area for considering the swirl intensity. The liquid film thickness strongly influencing on the formed drop size of the spray was measured using a new technique. The film thickness measurement technique proposed here, used the attenuation of fluorescence signal near the injector exit. The breakup length that is important for the flame location as well as the spray cone angle which influences on the ignition performance was measured using a backlit stroboscopic photography technique. From the experimental results, it is found that an increase in injection pressure decreased the film thickness and breakup length, and also enlarged the spray cone angle. A decrease in orifice length and tangential entry port area has a similar tendency of thinner film thickness, shorter breakup length and larger spray cone angle. In the present study, we proposed empirical models of the flow characteristics of the swirl injectors.

• 한국추진공학회지
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• 제23권1호
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• pp.1-8
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• 2019

스월/전단 동축형 인젝터를 통해 형성된 기체메탄-기체산소 확산화염의 동역학적 거동 및 구조분석을 위해 다양한 추진제 분사조건에 따른 연소실험이 수행되었다. 연구결과, 자발광 기법을 통해 가시화된 확산화염의 $OH^*$ 방사강도는 추진제 공급유량 및 운동량 플럭스 비 증가에 따라 높은 값을 나타내고 있으며, 스월을 가지는 화염은 그렇지 않은 것에 비해 더 우수한 반응성을 보였다.

• 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.

• 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.

• 한국군사과학기술학회지
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• 제9권4호
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• pp.137-144
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• 2006

단일요소 분사기(35kgf급)의 성능시험을 통해서 입증된 recess 2mm의 축소 모사된 로켓엔진(지상추력 250kgf급 다중요소 스월 동축형 분사기)을 설계, 해석, 제작, 시험하고, 이를 통하여 주요한 설계변수에 대한 검증과정을 수행하였다. 단일요소 및 다중요소 인젝터의 분무현상을 수치 해석적으로 모사하여 중첩에 의한 분무의 변화를 해석적으로 고찰하고 적용성 및 타당성을 확인하였다. 그리고 다중요소 분사기에 대한 연소성능시험을 통하여 엔진의 정상 연소성능을 평가하고 이를 단일요소 인젝터의 연소성능과 비교하여, 대형 로켓개발에 앞서 필요한 각 축소모델에 대한 특정 스케일에서의 다중요소 인젝터에 의한 연소성능을 평가하고 설계 자료를 확보, 합리적인 분사기 설계 변수자료를 확립하였다.