• 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 of Propulsion Engineers
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• v.17 no.4
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• pp.81-88
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• 2013

It was designed and tested at the design point that an oxidizer rich preburner for a staged combustion liquid rocket engine propelled by kerosene and LOx. The oxidizer rich preburner was designed as some of LOx injected from the mixing head was burned with kerosene and the rest of LOx injected from injection holes in the regenerative cooling chamber was vaporized by combustion gas. The preburner is operated at OF ratio of 60 and combustion pressure of 20 MPa. The Preburner has a honey-comb type mixing head with simplex swirl injectors, a turbulence ring improving combustion stability and uniformity of product gas temperature distribution, and a nozzle simulating the duct. With the combustion test results at the design point, the oxidizer rich preburner showed high combustion stability and uniformity of product gas temperature distribution.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.106-109
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• 2012

It was designed and tested ignition that an oxidizer rich preburner for a staged combustion cycle liquid rocket engine propelled by kerosene and LOx. Operation conditions of the preburner are about 60 of OF ratio and 20 MPa of combustion pressure. Ignition characteristics were compared by propellants flowrate. As the results, the higher propellants flowrate, the shorter the ignition delay time and the higher ignition stiffness. The ignition delay time was affected by incoming the oxidizer flowrate through the refrigerative cooling channels. The oxidizer flowrate from the cooling channels decreased by inflow of combustion gas during initial ignition. The oxidizer flowrate of the cooling channels increases, it is rapid recovery by cooling effect, eventually the ignition delay time decreases.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.57-63
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• 2007

The oxidizer-rich preburner is applied to the high efficiency closed cycle rocket propulsion system. This system is generally operated on oxidizer-fuel mixture ratio over than 50. The spray quality and mixing performance are very important for stable combustion of this preburner. This paper presents basic design concept and spray characteristic of the oxidizer-rich preburner injector and this result could be applied to the development of the oxidizer rich preburner system.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.149.1-149.1
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• 2012

고성능 다단연소싸이클 엔진은 산화제과잉 예연소기를 사용한다. 예연소기 후류에 위치한 배관 및 연소기 헤드 등은 고온/고압 산화제 과잉 환경에 놓이게 되며, 운용 조건에서는 국부적으로 온도를 상승시키는 외부 발화제에 의하여 녹는점보다 낮은 온도에서 재질이 발화될 수 있다. 따라서, 이러한 환경에 적합한 재질 및 코팅은 내산화성, 내인화성 및 자발화성도 중요하나, 외부 발화제에 의한 내발화성이 가장 중요한 특성이 된다. 여기서는 이러한 환경에 적합하며 지상 시험용 노즐 및 배관에 적용될 수 있는 재질 및 코팅에 대하여 조사한다. 러시아는 이미 이러한 환경에 적합한 재질 및 코팅들을 개발하여 RD-170, 180에 적용 중이다. 그러나 미국은 최근에 이러한 연구를 시작한 것으로 추정된다. 따라서 자료 접근이 가능한 범위에서 러시아의 재질 및 코팅을 조사하며, 미국 자료에서는 산소 시스템 안전 등과 같이 간접적인 자료들을 통하여 대체가 가능한 후보 재질 및 코팅을 조사한다. 다단연소싸이클 연소시험 배관에 적용할 수 있는 방법은 다음과 같다. 코팅 없이 Monel K500을 사용하거나, OFHC 혹은 Ni 라이너에 고강도 외피를 사용하는 방법이 있으나, 두 방법 모두 재질의 가격 및 수급, 라이너 적용 방법 등이 어려울 수 있다. 국내에서 산화제과잉 가스 환경에서 적용할 수 있는 법랑을 개발하거나 수급이 용이한 법랑을 찾아 오스테나이트 스테인리스강에 적용하는 방법이 있다. 이 방법은 외부 발화제에 대한 내발화성을 증가시키는 경제적이고 용이한 방법으로 판단된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.869-872
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• 2011

Ignition tests of an oxidizer rich preburner for a staged combustion cycle liquid rocket engine were performed to evaluate combustion performance. Design operation conditions of the tested oxidizer rich preburner are about 60 of OF ratio and 20 MPa of combustion pressure. The entire kerosene and some LOx injected into the mixing head is burned in combustion chamber and the remaining LOx injected through center holes of combustion chamber is vaporized. Full flow ignition method with hypergolic fuel was used. Each propellant was supplied in two stages for soft ignition. Test results, low frequency oscillation was occurred in low flow rate conditions under 45% of design flow rate. Stable ignition in the course of design combustion pressure was able to induce by minimization of low flow rate ignition region to escape low frequency oscillation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.923-927
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• 2017

Metal exposed to high temperature/high pressure/oxidizer-rich environment may cause rapid oxidation(ignition and combustion). Therefore, this study was performed for the selection of metal appropriate for high temperature/high pressure/oxidizer-rich environment. In order to make the high temperature, high pressure and oxidizer-rich environment, the test facility utilizing the catalytic reaction of hydrogen peroxide was constructed and the metal oxidation and ignition of the STS series metals were evaluated. The result showed that the change of the selected material (discoloration) and the surface roughness were observed, but the change in the weight and thickness of the specimen was not significant.

• 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.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.67-75
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• 2013

The numerical analysis for the verification of preburner's cooling characteristics applying to kerosene-LOx rocket engine has been fulfilled. The distribution of combustion gas properties in primary combustion zone was calculated by the mixture ratio based on head injector arrangement, the properties of oxygen flowing in wall channels as coolant were applied under real-gas conditions, and multi-phase mixing model was employed to calculate the mixing process of primary combustion zone with liquid oxygen which was used for wall cooling. The results of numerical analysis were compared with the experimental results, hence thermo-physical properties in cooling channels and a combustor could be quantitatively identified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.65-69
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• 2012

An oxygen rich preburner was tested and the responses from the pressure sensors were studied with FFT analysis. Since the limited capability of the static sensor, less than 250 Hz frequency domain was investigated and compared to the results of the dynamic sensors. As a result, 60 Hz harmonics were presented dominant in the combustion pressure and oxygen inlet pressure. While similar harmonics were shown with the dynamic sensor, it indicated that harmonics less than 60 Hz were very minor and the high frequency is more important.