• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.97-102
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• 2013

A prestudy on expendable turbine engine for high-speed vehicle was conducted. After two possible mission profiles were established to decide the engine requirements, design point analysis was performed with the values of design parameter which were obtained from similar class engines, references, etc. The results showed that specific net thrust and specific fuel consumption with turbine inlet temperature of 3,600 R are 2,599.4 ft/s and 1.483 lb/(lb*h) respectively at the flight condition of sea level, Mach 1.2. It was also found that major design parameters for determining maximum net thrust were turbine inlet temperature for low supersonic and transonic flight speed and compressor exit temperature for high supersonic flight speed from the results of performance analysis on the two possible mission profiles. In addition, simple turbojet engine with an axial compressor, a straight annular combustor, an one stage axial turbine and a fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost lightweight turbine engine.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.247-255
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• 2016

The purpose of this study is to investigate unsteady-state characteristics of a pintle thruster with various pintle speed. Based on steady state experimental results, non-linear pintle stroke equation is obtained and applied to the unsteady state experimental system. For the unsteady state experiments, three different pintle speeds are used: 3.10 mm/s, 5.65 mm/s, 10.83 mm/s, respectively. Results show that backward pintle stroke results in faster convergence time because of high chamber pressure during backward pintle stroke sequence. During the forward and backward process, thrust curve shows singular points. These phenomenons is caused by variation of mass flow rate, which is mainly due to changes of both chamber pressures and nozzle throat area. This behavior becomes distinctive for a faster pintle speed case.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.56-61
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• 2012

Fuel-side cold-flow tests were performed on the technology demonstration model of a 75 ton-class liquid rocket engine combustion chamber for the first stage of the Korea space launch vehicle II. Pressure drop in the cooling channels of the combustion chamber was measured by changing fuel mass flow rate through a pressure regulating system. Pressure drop in each segment of the chamber could be obtained and a lot of pressure drop was caused by high flow velocity in the nozzle throat segment. The accuracy of a hydraulic analysis method for calculating a pressure loss in cooling channels could be verified by applying it to the cold-flow test conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1091-1097
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• 2015

Graphite material has been widely used for making the rocket nozzle throat because of its excellent thermal properties. However, when compared with typical structural materials, graphite is relatively weak with respect to both strength and toughness, owing to its quasi-brittle behavior, and gets oxidized at $450^{\circ}C$. Therefore, it is important to evaluate the thermal and mechanical properties of this material for using it in structural applications. This study presents an experimental method to investigate the fracture behavior of ATJ graphite at elevated temperatures. In particular, the effects of major parameters such as temperature, loading, and oxidation conditions on strength and fracture characteristics were investigated. Uniaxial compression and tension tests were conducted in accordance with the ASTM standard at room temperature, $500^{\circ}C$, and $1,000^{\circ}C$. Fractography analysis of the fractured specimens was carried out using an SEM.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.81-88
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• 2013

The component based propulsion modeling and simulation of an dual ramjet engine using Taylor-Maccoll flow equation and quasi 1-D combustor model. The subsonic and supersonic intake were modeled with Taylor-Maccoll flow having $25^{\circ}$ cone angle, the gas generator which transfers a pre-combustion gas into supersonic combustor was developed using Lumped model, and the determination of the size of nozzle throat of a gas generator was described. A quasi 1-D model was applied to model a supersonic combustor and the variation of temperature and pressure inside combustor were presented. Furthermore, the thrust and specific impulse applying fuel regulation by pressure recovery ratio and equivalence ratio were derived.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.243-246
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• 2008

The combustion characteristic of solid fuel with chamber pressure were experimentally studied in hybrid combustion. This paper was experimental confirmed whether solid fuel affected not only oxidizer mass flux but also chamber pressure. Poly-Ethylene(PE) was used as fuel, GOX was used as oxidizer. Chamber pressure was controled by nozzle throat diameter 6mm and 9mm. In low oxidizer mass flux, solid fuel regression rate was affected not only oxidizer mass flux but also chamber pressure. As well, the regression rate increase as chamber pressure increase with same oxidizer mass flux.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.78-84
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• 2020

The performance of pintle thruster is analyzed by using the pintle thruster performance analysis model which integrating the element models introduced in Part I. To verify the performance analysis, the results of the developed program are compared with the experimental data of kerosene/hydrogen peroxide liquid pintle thrusters. Based on the results, the characteristics of the pintle thruster are analyzed. The sensitivity analysis is performed to investigate the effect of thruster shape and operation parameters on performance characteristics using both OAT and scatter plot methods. The four performance parameters such as droplet diameter, film flow rate, O/F ratio, and nozzle throat diameter are evaluated to investigate their effects on characteristic speed, combustor pressure, and specific thrust.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.378-383
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• 2013

A butterfly throttle valve has been used to control the brake power of an SI engine by controlling the mass flow-rate of intake air in the induction system. However, the valve has a serious effect on the volumetric efficiency of the engine due to the pressure resistance in the induction system. In this study, a new intake air controlling valve named "Variable Geometry Throttle Valve(VGTV)" is proposed to minimize the pressure resistance in the intake system of an SI engine. The design concept of VGTV is on the application of a venturi nozzle in the air flow path. Instead of change of the butterfly valve angle in the airflow field, the throat width of the VGTV valve is varied with the operating condition of an SI engine. In this numerical study, CFD(computational fluid dynamics) simulation technique was incorporated to have an aerodynamics performance analysis of the two air flow controlling systems; butterfly valve and VGTV and compared the results to know which system has lower pressure resistance in the air intake system. From the result, it was found that VGTV has lower pressure resistance than the butterfly valve. Especially VGTV is effective on the low and medium load operating condition of an SI engine. The averaged pressure resistance of VGTV is about 49.0% lower than the value of the conventional butterfly throttle valve.