• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.81-82
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• 2009

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1122-1126
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• 2017

KSLV-II ullage motor is a type of the separation motor of Korea Space Launch Vehicle. Simultaneously operates with the retro Motor to perform the stage separation. The internal ballistics design, application of propellant composition, and the design of the combustion chamber and the canted nozzle were performed in accordance with the target performance of the ullage motor. Ti-6Al-4V alloy was applied to the combustion as material of chamber and nozzle. The heat resistant material of the nozzle was selected to ensure the heat resistance of the propellant containing a large amount of aluminum. And the combustion performance of the ullage motor satisfying the KSLV-II requirements was secured by performing the ground combustion test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.73-79
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• 2010

Propellant tank pressurizing gas injector is used in the pressurization system of liquid propellant rocket to reduce incoming gas velocity and distribute the gas in the tank. Temperature distribution in the propellant tank ullage is varied according to the gas injector shape, and it has influence on the required pressurant gas and thermal phenomena in the tank. In this paper, diffuser type gas injector was studied to make the ullage have stratified temperature distribution. Injected gas flow at the outlet of prototype diffuser was visulized using particle image velocimetry method and it was compared with the results of calculation. Calculation was well agreed with measurement and was used as an inlet condition of propellant tank ullage calculation.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.83-83
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• 2004

상용프로그램인 AMESim을 이용하여 제어밸브 성능시험설비에 대한 Transient 구간에서 문제점 발생 확인과 동시에 시스템에 최적화를 통한 비용 절감효과를 위해 본 Simulation을 수행하였다. 가압 자동 조절 시스템은 직렬식과 병렬식 두 가지에 대해 고려했을 경우 직렬식이 더 타당함을 확인하였고, 특히 Tank Ullage의 압력 분포를 보면 직렬식에서 Fluctuation이 약 $\pm$0.2%이고, 병렬식에서 약 $\pm$0.7%가 됨을 보았다. (중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1202-1208
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• 2010

The prediction of the required pressurant mass for maintaining the pressure of propellant tanks during propellant feeding is an important issue in designing pressurization system. The temperature of pressurant fed into propellant tank is the critical factor in the required pressurant mass and is one of the most crucial design parameters in the development of pressurization system including designing the weight of pressurant tanks and the size of heat exchanger. Hence a series of propellant drainage tests by pressurizing propellant stored in a cryogenic propellant tank have been performed with measuring the temperature distribution inside ullage and the required pressurant mass according to the temperature condition of pressurant. Results shows that the required pressurant mass decreases as the temperature of pressurant increases. However, the rate of the actual pressurant mass to the ideal required pressurant mass increases.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.1048-1053
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• 2009

It proposes an simple and intuitive method that calculates the equilibrium pressures of a propellant tank by appling the mass conservation principle on the helium in the liquid propellant and in an ullage volume of the propellant tank. A propellant loading analysis program is developed and validated against the existing reference data. And it has applied to the present developing program, COMS Chemical Propulsion Subsystem and the results are compared, it may use to develop a technology of the next geostationary complex satellite's propulsion system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.687-692
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• 2004

For the prediction of sloshing in the propellant tank of rocket vehicle utilized in RVT (reusable rocket vehicle testing) conducted by ISAS/JAXA, the flow field in the propellant tank during the ballistic flight was experimentally reproduced with the sub-scale model of it. The lateral acceleration as large as about 0.8 G was provided with a mechanical exciter and the deformation of liquid surface in the vessel was visualized with a high-speed camera. The several con-figurations of damping devices were installed and tested in the vessel, which should keep the ullage gas away from the outlet port. It was consequently suggested that the combination of a baffle plate and a perforated cylinder could be effective against the gas suction before the re-ignition of the engine. The sloshing phenomena were also simulated with the CFD code, called CIP-LSM. The numerical results showed good agreement with the corresponding data obtained in the experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.279-284
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• 2008

Propellant pressurization system in liquid rocket propulsion system plays a role in supplying pressurant gas at a controlled pressure into the ullage space of propellant tanks. The most important design parameter for such propellant pressurization system is the temperature of pressurant gas fed from pressurant tank, which is placed inside of cryogenic propellant tank. Such pressurant is gaseous state, of which density is very sensitive to the temperature of pressurant. Previous investigation dealt with thermal correlation of pressurant and external fluid at room temperature. This study investigates the temperature variation of cryogenic pressurant (GHe) at the time when the pressurant is coming out of pressurant tank, which is submerged in a liquid oxygen, experimentally as well as numerically.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.168-175
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and Test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test Facility).

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.9-17
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• 2007

The performance test of recirculation line in propellant feeding system was carried out. Liquid oxygen was used as cryogenic propellant and helium was used as recirculation promotion gas. Tests were done in cases at atmospheric pressure and at pressure of 4 barg in the ullage space of propellant tank. Liquid oxygen recirculation flowrate with helium injection flowrate and temperature distribution along the line were measured. There was appropriate helium injection flowrate for gas-lift recirculation system. Test data were used to make calculation program by test data correlation method. In this paper the procedure of calculation was presented and the results were compared to test data.