• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.54-61
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• 2007

Propellant pressurization system in liquid rocket propulsion system plays a role 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. Such pressurant is gaseous state, of which density is very sensitive to the temperature of pressurant. Generally for the propulsion system, which requires high thrust and is consisted of cryogenic propellant the pressurant is stored at high density and high pressure to reduce the weight of pressurant tanks, which are placed inside of cryogenic propellant tank. That is called cryogenic storage pressurization system. This study investigates the temperature variation of pressurant at the time when the pressurant is coming out of pressurant tank experimentally as well as numerically. Fluids used in this study are air and liquid oxygen as outer fluid and gaseous nitrogen and gaseous helium as pressurant respectively.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.125-132
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• 2010

Estimation of pressurant mass flowrate and its total mass required to maintain propellant tank pressure during propellant outflow is very important for design of pressurization control system and pressurant storage tank. Especially, more pressurant mass is required to maintain pressure in cryogenic propellant tank, because of reduced specific volume of pressurant due to heat transfer between pressurant and tank wall. So, basic model for propellant tank ullage calculation was proposed to estimate ullage and tank wall temperature distribution, required pressurant mass, and energy distribution of pressurant in ullage. Both test and theoretical analysis have been conducted, but only theoretical modeling method was addressed in this paper.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.54-62
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• 2011

The pressurant mass required for propellant tank pressurization with operating condition variation was estimated by using the numerical model already developed for this purpose. The model was applied to the concept design results of KSLV-II first stage oxygen tank. The supplied pressurant temperature, oxygen volumetric flow rate, and the ratio of length to diameter of the tank were selected as variables. The required pressurant mass and mass flow rate, collapse factor, ullage temperature distribution were predicted, and the results showed that the pressurant temperature had the largest effect on the amount of the required pressurant mass. The pressurizing efficiency of the propellant tank was calculated through analyzing energy distribution in the ullage. It was found that the gas-to-wall heat transfer in the ullage was dominant, and much of the pressurant energy was lost to tank wall heating.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.83-90
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• 2013

In this paper, the energy flows related to cryogenic propellant tank ullage were understood and pressurization efficiency of the tank was calculated using propellant feeding test data with the help of calculation program. The related energy flow terms and calculation method of each terms were described. Three test data of different tank pressure and incoming pressurant temperature were used. Under the test conditions, the pressurization efficiency was low in the range of 13.9%~19.3%. The proportion of energy loss to the incoming pressurant energy was in the range of 55.2%~67.6%. The energy loss to the propellant tank wall was the biggest one. If the temperature of incoming pressurant was the same, the rates of each energy flows to the incoming energy were almost the same regardless of the propellant tank pressure. The collapse factor of propellant tank was calculated using test data, and the relation of it to the heat loss rate was observed.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.74-74
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• 2004

액체추진제를 사용하는 위성 발사체의 경우 추진제탱크에 저장된 추진제를 추력을 발생하는 연소실에 공급하기 위하여 헬륨 등의 가압제를 사용한다. 본 연구에서는 액체추진제 로켓엔진의 산화제인 극저온의 액체산소를 저장하고 있는 탱크 내부에 설치된 별도의 탱크에 저장된 극저온/고압의 헬륨을 고온으로 열팽창 시켜 추진제 탱크로 재유입하여 추진제를 가압하는 시스템에 사용되는 가압제 열팽창용 열교환기의 개발을 위한 기초 설계를 수행하였다. (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.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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• 2007.04a
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• pp.58-64
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• 2007

Propellant pressurization system in liquid rocket propulsion system plays a role 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.

• 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.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.124-132
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• 2003

This paper described the structural design and the fabrication procedure of KSR-III composite pressure tank. The type of the composite pressure tank was COPV(Composite Overwrapped Pressure Vessel). A non-load sharing liner was made of aluminum 6061-0 and the liner provided a helium gas seal. The composite pressure tank was winded using T700 carbon/epoxy on the liner. Because the aluminum liner was thin, multiple cure cycles were applied to the filament winding technique. The multiple cure cycles prevented the liner-cylinder from losing a circular shape. A fitting force at the metallic boss was spread to the carbon fiber by a boss ring. The boss ring also prevented a local deformation at the boss part.