• 한국안전학회지
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• 제15권3호
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• pp.30-39
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• 2000

The present paper deals with the numerical simulation for the spray characteristics with swirling turbulent flows and dilution flows from swirl injectors in a simplified can type of gas turbine combustor. The main objective is to investigate the characteristics of swirling turbulent flows with dilution flows and to provide the qualitative results for the spray characteristics such as the droplet distribution and Sauter Mean Diameter(SMD). The gas-phase equations based on Eulerian approach were discretized by Finite Volume Method, together with SIMPLE algorithm and the Reynolds -Stress-Model. The liquid-phase equations based on Lagrangian method were used to predict the droplet behavior. The results of preliminary test are generally in good agreement with experimental data, and show that the anisotropy exists in the primary zone due to swirl velocity and injected air from primary injector, and then gradually decays due to turbulent mixing and consequently near-isotropy occurs in the region between primary and dilution zones. For the spray characteristics, it is indicated that the swirling flows of primary jet region increase the droplet atomization. In addition, it is showed that the swirling flows at the inlet region lead the air-fuel mixture to be distributed near the igniter and can significantly affect the spray behavior in the primary jet region.

• 한국항공우주학회지
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• 제39권4호
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• pp.341-347
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• 2011

본 연구는 기존의 인젝터와 새로운 형태의 인젝터를 비교분석 함으로써 소형 추력기의 성능을 연구하였다. 기존의 인젝터는 볼록한 표면에 8개의 노즐로 구성되어 액체 추진제를 분사하는 형태로 제작되었다. 우리가 제안한 새로운 형태의 인젝터는 오목한 표면에 4, 5, 6, 8, 9개의 노즐로 구성된 충돌형 인젝터이다. 노즐의 구멍을 통해 분사되는 액체추진제는 축 방향으로 한 점에서 부딪히게 설계되었으며, 이는 분사되는 액체 추진제의 입자를 더욱 세분화하여 사방으로 일정하게 분무할 수 있도록 하였다. 본 논문에서는 전산유체역학, 입자 유속계 및 고속 카메라를 이용하여 분무 가시화 및 인젝터의 성능을 연구 하였다.

• Journal of Yeungnam Medical Science
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• 제6권2호
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• pp.63-70
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• 1989

This paper describes to design and to examine the mechanical characteristics of high frequency jet ventilator. The device consists of Phase lock loop(PLL) system, solenoid valve driving control part and Air regulating system. This study is carried out by changing several factors such as endotracheal tube(E.T. tube)diameter, injector cannula diameter, 1%, and frequency(breaths/mim.) having direct effects on the gas exchange as well as parameters of the entrained gas by venturi effects, so as to measure the tidal volume and minute volume. This system characteristics were as follows : 1) Frequency : 6-594bpm 2) Inspiration time : 1-99% 3) Variance of input air pressure : 1-30PSI.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.5-7
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• 2012

This study presents relations between the time lag and interaction index of the impinging-jet injectors using time lag model in a model chamber. To analyze the response of the flame, 5% amplitude of oxidizer velocity is artificially perturbed at a resonance frequency. At the mixing point of fuel and oxidizer, which determines the characteristic length, the relationship between velocity perturbation and heat release rate is quantified by combustion parameters of interaction index and time lag. As the improved method to apply the time-lag, the method using the average velocity obtained from numerical results is suggested.

• 한국분무공학회지
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• 제12권1호
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• pp.45-57
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• 2007

This paper presents both experimental and numerical studies regarding nozzles used for the SI engine application, particularly for the intake-port fuel injection type. The atomization mechanism of the multi-hole plate nozzle was investigated experimentally. It was found that the nozzle design added turbulence into the liquid-film jet and the jet disintegrated rapidly. Based on the results, various plate types for the nozzle were developed and tested; six hole nozzle for liquid jet interaction, plate-type nozzle with flat duct channel, and the simpler structured nozzle. The spray characteristics of the prototype nozzles were examined experimentally while the internal flow of the nozzle was investigated computationally. It was shown that turbulent liquid-film was injected and atomization quality was improved by controlling the internal flow condition of the plate-type nozzle.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.79-84
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• 2004

This paper report our preliminary results of characterizing the jet structures of kerosene injection into quiescent atmosphere and a Mach 2.5 crossflow at various preheat temperature. A heating system has been designed and tested that can prepare heated kerosene of 0.8 kg up to 670 K at a pressure of 5.5 ㎫. Temperature measurement near the injector shows that the temperature of pressurized kerosene can be kept constant during the experimental duration. Comparison of kerosene jet structures in the preheat temperature range of 290-550 K demonstrates that with injection pressure of 4 ㎫ the jet plume turns into vapor phase completely at injection temperature of 550 K, while keeping the penetration depth essentially unchanged. The results suggest that the injection of vaporized fuel would improve the performance of a liquid hydrocarbon-fueled supersonic combustor because the evaporation process is now omitted.

• 한국추진공학회지
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• 제6권2호
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• pp.37-44
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• 2002

액체로켓엔진에 사용되는 2-유체 동축형 분사기의 분무 연소 특성을 수치적으로 해석하였다. 가스 역학적 상호작용에 의한 미립화 및 그에 따른 물리 현상들에 대해 유동에 대한 보존방정식과 이론식들을 적용, 수치화하여 액체 제트의 상태, 제트의 속도, 제트의 붕괴길이, 액적의 크기등을 예측 하였으며, 액체제트 분사공 크기에 따른 미립화의 변화를 고찰하였다. 모델 검증을 위하여 액체 제트의 접촉길이와 액적의 크기를 기존의 실험결과와 비교하였으며, 그 결과 정성적으로 일치함을 나타내었다. 액체 제트의 접촉길이는 분사공의 직경이 증가할수록 짧아지고 액적의 크기도 분사공의 직경이 증가할수록 작아진다. 액체 제트는 박리율 증가에 따른 분무화에 의하여 단면적이 감소되며, 그에 따른 질량유속의 보존과 가스로부터의 운동량 화산에 따라 미립화가 활발해지는 영역으로부터 그 속도가 급속히 증가된다.

• 한국추진공학회지
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• 제9권4호
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• pp.48-54
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• 2005

액체 산소(LOx)와 Jet A-1(Jet engine fuel)을 추진제로 하는 소형 액체 로켓 연소기에서 막 냉각의 효과에 관한 실험적 연구를 수행하였다. 막 냉각제(Jet A-1과 물)는 막냉각장치를 통해 분사되도록 하였다. 막 냉각 유량 변화에 따른 연소기의 외벽온도 및 막 냉각 길이는 추진제 혼합비, 연소실 압력 및 막냉각장치의 형상 변화(분사각)에 따라 비교하였다. 막 냉각에 따른 특성속도 효율의 손실도 막 냉각제를 물과 Jet A-1을 사용하였을 경우에 대해서 각각 구하였다. 연소실 압력의 증가에 따라 노즐에서의 외벽 온도는 증가하였으나, 퍼센트 막냉각 유량이 9% 이상인 경우에 연소실에서는 거의 영향을 받지 않았다. 특성속도는 퍼센트 막냉각 유량이 9% 이상일 때 추진제 혼합비에 영향을 받지 않았다.

• 한국추진공학회지
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• 제17권2호
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• pp.1-8
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• 2013

모형 연소실에서 충돌형 분사기의 연소 안정성 평가를 위해 시간지연(time lag)과 간섭인자(interaction index)의 관계를 연구하였다. 산화제 분사 속도의 5%에 해당하는 섭동을 공진주파수로 인위적으로 가진하여 이에 대한 화염의 응답특성을 분석하였다. 연료와 산화제의 혼합지점인 충돌점들, 즉, 특성길이 위치에서 속도섭동과 열방출율 섭동간의 관계를 시간지연 모델을 이용하여 나타내었다. 시간지연을 정량화하는 개선된 방법으로서, 수치해석을 통해 얻은 결과로부터 분사기 출구면으로부터 충돌점까지 평균속도를 이용하는 방법을 제안하였다. 축방향의 평균속도가 증가할수록 시간지연이 짧아지는 경향성을 확인할 수 있었다.

• 한국분무공학회지
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• 제7권4호
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• pp.32-41
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• 2002

The breakup characteristics of liquid sheets formed by like-doublet injector were investigated in the cold-flow and atmospheric ambient pressure condition. The sheet breakup wavelength, which induces the sheet to be broken into ligaments, as well as the sheet breakup length, which is important for the flame location, was measured using a stroboscopic light. The liquid ligaments are formed intermittently after the breakup of sheet, and the wavelength of ligaments has been believed to have a relation to the combustion instability of liquid rocket engine. Therefore, the wavelength of ligaments and the breakup length of ligaments into fine drops were also measured. Since these spray characteristics are affected by the flow characteristics of two liquid jets before they impinge on each other, we focused on the effects of orifice internal flow such as the cavitation phenomenon that occurs inside the sharp-edged orifice. From the experimental results, we found that the liquid jet turbulence delays the sheet breakup and makes shorter wavelengths for both sheets and ligaments. Since the turbulent strength of sharp-edged orifice is stronger than that of round-edged orifice, the shape of orifice entrance results in large differences in the spray characteristics. Using these results, we proposed empirical models on the spray characteristics of the like-doublet injector, and these models are believed to provide some useful and actual data for designing liquid rocket combustors.