• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.279-282
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• 2011

The analysis and experimental results for the bellows of gasgenerator liquid oxygen shut-off valve are presented. The analyses are performed using EJMA (Expansion Joint Manufacturing Association) standard and the commercial FE (finite element) analysis program, Abaqus v6.9, at room and cryogenic temperatures. The results include the spring rate, the stress and the fatigue life of the bellows. The effects of the contact and material plasticity on the FE analysis results are also analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.64-70
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• 2005

The overall results of hot firing tests of fuel-rich gas generator with impinging injector at design and off-design points are described. The gas generator consists of an injector head with impinging injector, a water cooled combustor wall, a turbulence ring to enhance mixing, an instrument ring measuring temperature and pressure and a nozzle. The combustion tests were successfully performed without damage of gas generator. Test results show that the outlet temperature is not dependent on residence time of hot gas within 4～6msec but dependent on chamber pressure. The relation between outlet temperature and combustion efficiency resulting from measured pressure, mass flow rate and area of nozzle throat is shown. The overall O/F ratio is the critical parameter to determine the outlet temperature and the linear correlation between two parameters is established.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.89-96
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• 2006

The combustion temperature in gas generator should be kept below around 1,000K to avoid any possible thermal damages to turbine blade by adopting either fuel rich or oxidizer rich combustion. Thus, non-equilibrium chemical reaction dominates in the gas generator. Meanwhile, Kerosene is a compounded fuel mixed with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focus to model the non-equilibrium chemical reaction of kerosene/LOX with detailed kinetics developed by Dagaut using PSR(Perfectly stirred reactor) assumption. Also, droplet evaporation time is taken into account by calculating for the residence time of droplet and by decoupling reaction temperature from the reactor temperature. In Dagaut’s surrogate model for kerosene, chemical kinetics of kerosene consists of 1592 reaction steps with 207 chemical species. The comparison of calculation results with experimental data could provide very reliable and accurate numbers in the prediction of combustion gas temperature, species fraction and other gas properties.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.58-63
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• 2009

The global restriction on pollutant emissions and the soaring of crude oil price are expected to result in the change of future transportation system. Hydrogen is considered to be the leading candidate as an alternative energy source before other new alternative energy sources emerge. Scientists anticipate that hydrogen fuel gas turbine engine and fuel cell will be the power plant of the aircraft in the near future. To realize the aircraft powered by fuel cell system in the future, the technologies such as fuel cell with higher energy density, compressed gas or liquid storage system of hydrogen fuel, and efficient and lightweight electric motor have to be developed first.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.77-81
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• 2012

In a cryogenic propellant tank the pressurant is contracted due to heat loss and the propellant itself evaporates. On a restartable propulsion system such phenomena are more intensive because the propellant contacts with the pressurant on the larger surface during the coast flight. Such heat and mass transfer phenomena should be considered for estimating the amount of pressurant. On the hypothesis that the heat and mass transfer quasi-equilibrium is achieved during the coast flight, the calculation process of the equilibrium pressure is presented. On the process the amount of loaded helium on the Falcon-1 second stage is calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.201-205
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• 2011

In a cryogenic propellant tank the pressurant is contracted due to heat loss and the propellant itself evaporates. On a restartable propulsion system such phenomena are more intensive because the propellant contacts with the pressurant on the larger surface during the coast flight. Such heat and mass transfer phenomena should be considered for estimating the amount of pressurant. On the hypothesis that the heat and mass transfer quasi-equilibrium is achieved during the coast flight, the calculation process of the equilibrium pressure is presented. On the process the amount of loaded helium on the Falcon-1 second stage is calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.121-124
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• 2008

This paper presents experimental results of dynamic characteristics of fuel-rich gas generators. Pressure fluctuation measurements in the chamber and manifolds have been analyzed. Gas-generator-alone tests revealed stable combustion regardless of a chamber pressure but low-frequency combustion instabilities occurred for cases of turbine-manifold tests at chamber pressure conditions below 50 bar. The instabilities are considered as an axial resonant mode and acoustic intensity increases along with a chamber pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.246-249
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• 2009

Test and launch facilities which use oxygen as the propellant of a launch vehicle have hazards of fire and explosion by the leakage of oxygen. Also, the personnel operating the facilities, which use the high-pressured gases like nitrogen and helium in the closed room, is exposed to the hazard of death from suffocation. Consequently, we should keep out of the hazards and the accidents by monitoring the contents of oxygen in the air. The method and the system construction for monitoring oxygen contents in the air and the results from its application to Naro space center are described on this paper.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.608-617
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• 1997

전자빔 용해법에 의해 고순도 티타늄잉고트 및 버튼시편을 제조하였다. 이들 중 18개의 금속불순물을 GDMS(Glow Discharge Mass Spectrometry)로 그리고 탄소, 질소, 산소의 함량을 고온연소법으로 측정한 후 이들과 전기비저항, 경도와의 관계를 조사하였다. 99%와 99.6%스폰지를 용해한 경우 대부분의금속불순물들이 대폭 감소하는 큰 휘발 정련효과가 나타났으며 비금속불순물들의 경우는 장비의 진공상태에 따라 큰 영향을 받으며 정련효과를 기대할 수 없었다. 금속 불순물중 철은 가장 제거하기 어려운 원소로 밝혀졌으며 이는 원료 스폰기중에서 철이 주불순물이기 때문이며 추가적인 예비정련이 필요한 것으로 나타났다. 상온 및 액체질소온도에서의 전기비저항은 가스불순물의 량이 증가함에 따라 직선적으로 증가하였으며 이들의 저항비($\rho$$_{RT}$ /$\rho$$_{N2}$)는 가스불순물의 총량이 1,000ppm이하의 경우 불순물량이 감소함에 따라 급격하게 저하하였으며 이 이상인 경우 완만하게 감소하였다. 이들의 경도는 가스불순물의 량이 증가하였으며 산소당량의 평방근에 비례하는 것으로 나타났다.다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.151.1-151.1
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• 2012

우주발사체와 발사지원설비를 연결하여 추진제 공급과 전기신호 송수신 등을 가능하게 하는 메커니즘을 엄브리칼 장치라고 한다. 국내 우주발사체의 경우 액체산소와 케로신을 추진제로 사용하며, 질소, 공기 및 헬륨 등의 가스를 밸브구동, 공간 퍼지, 추진제 가압에 이용한다. 본 논문에서는 우주센터의 발사대설비에 적용된 엄브리칼 장치 중 추진제 및 고압가스 공급을 위한 자동체결장치(auto coupling device)의 구성, 기능 및 발사 준비를 위한 프로세스에 대해 기술하고 있다. 자동체결장치는 발사체 하부 두 곳에 연결되며, 산화제 공급측의 체결장치(coupling device 1)와 연료 공급측의 체결장치(CD 2)로 구성된다. 이 장치는 발사체와의 접촉면에서 기밀을 확보한 상태에서 내부의 탱크, 밸브, 인터스테이지 등에 추진제 및 각종 가스를 공급하는 통로역할을 하며, 발사준비가 완료된 후에는 발사체 이륙 전 또는 이륙과 동시에 발사체로부터 자동으로 분리된다. 각각의 체결장치 구성품으로는 발사체 이륙시 발생하는 고온의 화염으로부터 장치를 보호하는 PD(protective device), 접촉면에 기밀을 제공하고 추진제 누출을 방지는 MCP(multi-channel plate), 접촉면을 보호하기 위한 덮게, 각종 연결 배관의 전진과 후진을 위한 캐리지, 발사체와의 체결을 지지하는 그립 등이 있다. 발사 준비를 위해서 사전에 장치의 독립운용시험을 통해 각 구성품의 상태와 기능을 점검하고 장치의 작동성을 검증한다. 이후 발사체를 모사하는 기체 및 관제설비와 종합적으로 연계 시험과 모사시험을 수행하여 최종적으로 발사준비상태를 확인하게 된다. 이러한 자동체결장치의 운용 경험은 한국형발사체의 지상지원설비 개발에 활용할 수 있을 것이다.