• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.92-100
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• 2010

Combustion stability rating tests of 75-tonf-class thrust chamber for technology demonstration were carried out at a low pressure. Two kinds of mixing heads were used in this study. One of them has injectors of 631 and the other has injectors of 721. Mixing head with injectors of 631 showed a self-oscillation instability at the chamber pressure of 30 bar. Mixing head with injectors of 721 showed that a high frequency combustion stability was maintained under the same pressure and the same mass flow rate. But mixing head with injectors of 721 generated a self-oscillation instability at the chamber pressure of 20 bar and it was found that stability boundary region was changed due to the configuration of a mixing head from these results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.288-293
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• 2006

The combustion performances and characteristics of the subscale liquid rocket combustion chamber are discussed in this paper. Subscale combustion chamber is composed of mixing head, ablative cooling cylinder, and water cooling nozzle. The mixing head has eighteen coaxial swirl injectors and one center coaxial swirl injector for ignition. The mixing heads employing the injectors of low different recess length are considered in this paper. The results of the firing test, comparison of performance, and characteristics of static and dynamic pressures of the four different mixing heads are described. The characteristics of combustion at design and of design points are also discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1140-1147
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• 2009

Flow analyses have been performed to investigate the uniformity of propellant flow through the fuel and oxidizer manifolds of a full-scaled gas generator for a pump-fed liquid rocket engines. Injectors were simulated as porous medium layers having equivalent pressure drops. The uniformity of propellants has been analyzed for 3 fuel rings and 3 injector head configurations. The mixture ratio distribution at the exit of injectors has been estimated from the mass flow rates of fuel and oxidizer. The best configuration of fuel ring and injection head was selected through these flow analyses.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.614-615
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• 2010

The propellants distribution of an oxidizer rich preburner was predicted by a simplified physical approach. The Mixing head is composed of honeycomb array of 7 fuel injectors and 24 oxidizer injectors. The OF ratio of the mixing head is 15. As results, the OF ratio of the central area is about 9 and the OF ratio of the wall area is about 30.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.135-141
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• 2005

The procedure of conceptual and detailed design of sub-scale combustor using bipropellant swirl or impinging injector with external or internal mixing for a liquid rocket engine are described in this paper. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has a injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl or impinging injector and 18 main swirl or impinging injectors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.231-238
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• 2010

Combustion stability rating tests under condition low pressure of a 75-$ton_f$ liquid rocket engine(LRE) thrust chamber were carried out. Mixing head with decreased number of injectors than that of the other but with the same mass flow rate to the combustion chamber showed self-oscillation instability in chamber pressure of 30 bar. The other combustion chamber with increased number of injectors showed that high frequency combustion stability was maintained under condition of same pressure, but self-oscillation instability was generated in chamber pressure of 20 bar which can be considered as stability boundary region of this mixing head.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.72-77
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• 2007

The combustion test results of the sub-scale combustor having dual swirl injector with internal mixing for a liquid rocket engine are described. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has an injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors of internal mixing. The combustion tests were successfully performed at design and off-design points without any damages on the injectors. Combustion characteristics velocity of 1756m/s was measured at design point. High frequency combustion instability was not observed but low frequency pulsations occurred at off-design conditions.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.151.2-151.2
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• 2012

터보펌프 구동에 사용된 가스발생기 생성가스를 연소기로 공급하여 주추력 발생에 사용하는 다단연소 사이클 로켓엔진은 고추력을 요하는 우주 발사체에 널리 사용되고 있다. 다단연소 사이클 로켓엔진에 사용되는 가스발생기를 예연소기라 부르며 케로신과 액체산소를 추진제로 하는 다단연소 사이클 로켓엔진에는 산화제 과잉 예연소기가 사용된다. 예연소기는 터보펌프 구동을 목적으로 하기 때문에 예연소기 생성가스의 횡단면 온도분포는 터빈에 의해 제한되는 온도범위 내에서 균일하여야 하며 넓은 운전영역에서 안정적인 연소가 이루어져야 한다. 산화제 과잉 예연소기는 모든 추진제가 혼합헤드를 통해 분사되는 방식과 추진제를 혼합헤드와 연소실로 나누어 공급하는 방식이 있다. 기술검증을 위해 산화제 일부와 연료를 혼합헤드를 통해 연소실에 공급하여 1차 연소시키고 나머지 산화제를 연소실 냉각채널을 거쳐 연소실 중앙의 분사공을 통해 연소실로 주입하여 기화시키는 형태로 최종적으로 연소압 20MPa, 혼합비 60에서 작동하는 산화제 과잉 예연소기를 설계하여 연소시험을 수행하였다. 혼합헤드에는 별도의 점화용 분사기 없이 전체 연료 분사기를 통해 점화용 연료인 TEA/TEB 혼합물을 분사하여 점화하였다. 추진제를 2단으로 공급할 수 있도록 고안된 가압식 연소시험 설비에서 10회, 누적 60초 이상의 연소시험이 성공적으로 수행되었다. 연소시험결과 넓은 작동영역에서 안정적 연소특성과 생성가스 온도 분포의 균일성을 확인할 수 있었다. 고온 고압의 산화제 과잉 예연소기 기술 확보를 통해 케로신/액체산소 다단연소 사이클 로켓엔진 개발을 위한 기술적 기반을 마련하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.102-111
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• 2004

The procedure of design and manufacture of sub-scale combustor using bipropellant swirl injector with external mixing for a liquid rocket engine are described. The results of cold flow test, ignition test and combustion test of the sub-scale combustor are also given in this paper. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has a injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors. The cold flow, ignition and combustion tests were successfully performed without damage of combustor. Results of hot firing tests show that combustion efficiency meets the target of design and operations of start and stop cyclogram are stable and high frequency combustion instability does not occur.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.335-340
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• 2005

A study on the variation of combustion characteristics by injector geometries was conducted. Coaxial swirl injectors were used. Existence of swirl chamber and variation of a nozzle length become key parameters. Injectors were identified as open, closed and mixed type by existence of swirl chamber. Variation of nozzle length was made extruding the both nozzle along the axis while other design parameters remain the same. A uni-element combustor with ablative material liner and a water cooled nozzle made by oxygen free copper with outer stainless steel casing were used.