• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.251-254
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• 2004

Hybrid rockets have many advantages over solid and liquid rockets. Hybrid rockets put forth high $I_{sp}$ like liquid rockets in spite of simple structure and low cost. As oxidizer flow rate is increased, thrust of hybrid rocket is increased accordingly. In this study, lab-scale hybrid rocket is designed, fabricated and tested. This system consists of lab-scale hybrid rocket motor, ignition system, flow system and data aquisition system. In order to control oxidizer flow rate, we construct flow rate control system by using needle valve and stepping motor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.223-227
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• 2006

In this study, the combustion characteristics was studied with various oxidizer in hybrid propulsion system. In this experiments $GN_2O$ and GOX were used as oxidizer, and PE was used as fuel. The combustion behavior was explained by flame temperature with mass O/F ratio, and the use of $GN_2O$ as the oxidizer caused a increase in combustion efficiency with GOX in the same hybrid motor. The mass flow rate of gaseous oxidizer was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $0.0138{\sim}0.0427kg/sec$. As result, the empirical relation for oxidizer type was represented by mass flux of solid fuel, it was obtained with mass transfer number, and mass flux of oxidizer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.203-206
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• 2006

We have studied, for maximizing the total impulse of liquid propulsion system, Propellant Utilization System (PUS) to minimize outage of propellant. Propellant outage is mainly influenced by propellant mixture ratio during flight and real quantity of loaded propellant. If one employs cryogenic propellant, the variation of propellant density due to the temperature change has major effect on outage control. Feedback control of propellant level of each tank during flight could deplete both tanks simultaneously. To introduce this system, however, the mixture ratio control system of rocket engine is necessary.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.246-250
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• 2006

In general, combustion characteristic of hybrid propulsion was shown with the regression rate depending on only massflow rate of oxidizer But this empirical relation was not represented well effect of the thermo-chemical properties of solid fuel. So, in this study, the combustion characteristics was studied with the mass transfer number(B number) of solid fuel instead of regression rate with various fuel. The PMMA, PP, and PE were used as fuel, and gas oxygen as oxidizer in this experiment. The mass flowrate of gas oxigen was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $3.66\sim45.3g/sec$. As result, the empirical relation for mass flux of solid fuel was obtained with mass transfer number, and mass flux of oxidizer as follow; $\dot{m}^{'}_f\;=\;0.0175G^{0.55}B^{0.4}$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.812-818
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• 2009

A MOV(Main Oxidizer shutoff Valve) controls the flow rate of liquid oxygen into the rocket combustor by opening and shutting operations piloted by a pneumatic force. In order to improve the effective design for sealing parts of poppet and piston assemblies, the poppet assembly has been designed to be just contacted with the piston assembly. However, to avoid a gap at the poppet/piston contact surface and to evaluate the MOV operating performance, an analyze on the force balance during the closing motion have been performed. For the accuracy of the analysis, the friction forces and the hydraulic forces have been respectively obtained by experiments and CFD analysis. Through the analysis, some important design parameters such as the spring constant, poppet friction and orifice size in the force balance have been introduced and the required operation performance of the MOV has been proved feasible.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.613-615
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• 2009

This paper is to introduce Hanwha Aerospace R&D Center's development status of TVC(Thrust Vector Control) system and control valves for Korean space launch vehicles. With the successful development of KSR-III TVC system, Hanwha have developed TVC system and RCS control valves for KSLV-I. Also, in the advance research area of KSLV-II, Hanwha have participated in LOx and fuel flow control valves and LOx shut-off valve development in the engine supply system. Based on the accumulated experiences and technologies in the aerospace key components and system development, Hanwha will make an important contribution to KSLV-II development in the future.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.108-117
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• 2013

The oxidizer shutoff valve of a gas generator controls the mass flow rate of the propellant of a rocket engine using pilot pressure and spring the force of the valve. The developing oxidizer shutoff valve can be shut off if the pilot pressure is removed from the actuator. Therefore, force balancing is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure required to open the poppet and to determine the working fluid pressure at which the valve starts to close. Under cryogenic flow test as a tests level of C.R.T(Control Random Test), the chattering phenomena occurred due to much leakage of a metal seat section. The pressure for chattering of the oxidizer valve is predicted at about 11 bar using force balancing analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.58-67
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• 2023

Results of dry-run tests, cold-flow tests, and hot-firing tests performed to throttle a methane engine uni-element thrust chamber are covered in the paper. After installing flow control valves on the oxidizer and fuel supply lines of the methane engine combustion test facility, a number of dry-run tests were repeated so that the valves could reach set strokes quickly and stably. Then, cold-flow tests using liquid nitrogen and gaseous nitrogen were conducted to confirm the stable supply of the simulated propellants according to the valve control. Finally, using liquid oxygen and gaseous methane, hot-firing tests for fixed and continuous thrust control of 50% to 10% of the nominal thrust were successfully performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.203-207
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• 2007

In this study, the combustion characteristics of HTPB was studied in hybrid propulsion system. In this experiments HTPB was used as fuel, GOX was used as oxidizer. The mass flow rate of GOX was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $13.8{\sim}42.7g/sec$. The experimental result of HTPB was compared with the other studies of HTPB, and the combustion performance of HTPB was analyzed with that of PE. As a result, the homing rate and efficiency of HTPB as fuel were better than that of PE in the same hybrid motor.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.63-72
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• 2010

MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the steady operational state. Although it has been showed that a EM(Engineering Model) with a high discharge coefficient value compared with the TM(Technology Model) fills the overall performance requirements, additional design modifications in some critical parts of the EM were conducted to improve the performance. The configurations of the pressure-control body, the middle flange, and the rips of the inlet body of the EM were modified and the performance tests have been performed with test models. Consequently, the intended improvements have been verified by the performance tests.