• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.981-987
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• 2011

In this study, single cylinder engine experiment was carried out to investigate combustion characteristics spray guided direct injection spark ignition engine. In the result of engine experiment, it was shown that flammable window of injection timing was existed. The combustion efficiency increased with retarding injection timing, reaching a peak value, subsequent to decrease again. These results were likely due to the effect of ambient pressure on stratified-premixed mixture preparation. 150 bar injection pressure condition and retarded injection timing from the best combustion efficiency injection timing showed the highest IMEP value due to the advanced combustion phase of the maximum combustion efficiency condition. HC emission showed same trend of combustion efficiency, and smoke emission was increased as injection timing was retarded due to the increased locally rich area in the high ambient pressure. NOx emission showed decreasing trend as injection timing was retarded. This is likely due to the maximum in-cylinder temperature was decreased with retarded combustion phase.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.213-217
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• 2011

Unsteady numerical simulations of pintle nozzles were implemented for solid rocket thrust vector control. The variation of pintle location was considered using unsteady numerical techniques, and dynamic characteristics of various pintle models were investigated. In order to consider the variation of the pintle location, a moving mesh method was applied. The effects of shape and location of the pintle nozzle have been analytically investigated. And the results were compared with numerical results. The chamber pressure, mass flow and thrust are analyzed to take account dynamic characteristics of pintle performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.13-19
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• 2003

A supersonic ground test facility to develop Ramjet and SCRamjet(Supersonic Combustion Ramjet) engine should be able to simulate high altitude and high Mach number conditions including air total pressure, oxygen level and specific heat ratio at the combustion chamber entrance. The test facility also should simulate the effect of oblique shock wave caused by the flight vehicle. The test facility developed in this study is supersonic free-jet blowdown type, which consists of high pressure air supply source(maximum pressure=32MPa), air heater(vitiation type), supersonic diffuser, ejector, and test chamber(nozzle exit dimension=200mm$\times$200mm).

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.7
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• pp.1063-1071
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• 2004

Accurate heat release analysis of cylinder pressure data is important for evaluating performance in the development of diesel engine However, traditional single zone first law heat release model(SZM) has significant limitations due to the simplified assumption of uniform charge and neglecting local temperature inside cylinder during combustion process. In this study. heat release rate based on single zone heat release model has been evaluated by comparison with computational analysis results using Fire code which is based on multi-dimensional model(MDM). To overcome limitations due to simplicity of single zone assumption. especially the influence of specific heat ratio on gross heat release has been esteemed and newly suggested were the equation $\gamma$= $\gamma$(${T/T}_{max}$) which describes the variations of gases thermodynamic properties with mean temperature and maximum mean temperature inside cylinder Single zone heat release model applied with this equation is shown to give very good results over whole range of operating conditions when compared with computational analysis results based on multi-dimensional model.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.4
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• pp.53-62
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• 2003

A supersonic ground test facility to develop Ramjet and SCRamjet(Supersonic Combustion Ramjet) engine should be able to simulate high altitude and high Mach number conditions including air total pressure, oxygen level and specific heat ratio at the combustion chamber entrance. The test facility also should simulate the effect of oblique shock wave caused by the flight vehicle. The test facility developed in this study is supersonic free-jet blow down type, which consists of high pressure air supply source(maximum pressure=32MPa), air heater(vitiation type), supersonic diffuser, ejector, and test chamber(nozzle exit dimension=200mm${\times}$200mm).

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.52-60
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• 2020

This paper deals with an optimal output tracking control for open-cycle liquid propellant rocket engine. For this purpose, we modeled simplified mathematical model of open-cycle liquid propellant rocket engine and designed optimal output feedback control system using combustion chamber pressure. For design the closed-loop system of open-cycle liquid propellant rocket engine, we designed optimal output feedback linear quadratic tracking control system using the linearized model and demonstrated the performance of the controller through numerical simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.72-78
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• 2003

In this paper, the feasibility study and the parametric design of hybrid motor with HTPB/LOX were conducted for micro air launch system. Design results were compared with 1st stage of Pegasus XL for verification of hybrid motor. Results showed that hybrid motor replace solid booster if Isp of hybrid motor reaches 330sec. In addition, mission analysis was established for micro air launch system, and parametric design was conducted with design variables: number of port, initial oxidizer flux, and chamber pressure. And the region of Isp was identified by parametric study which satisfied design constraints and mission analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.297-300
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• 2017

A drastic pressure increment at the combustor inlet induced thermal choking is inevitable during scram-to-ramjet transitions. This phenomenon which is called by Non-Allowable Region(NAR) was observed on the excessive increment in the equivalent ratio. However, many studies were not investigated about factors which affects a variation of NAR. In the present study, a variation of NAR with regard to Mach number in the inlet of isolator is numerically and analytically analyzed. The conclusions from the investigation show that increasing the Mach number in the isolator inlet enlarged in the range of NAR.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.4
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• pp.63-74
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• 1989

It is well-known that the fuel injection system if a diesel engine has taken a more important place in understanding of diesel combustion process with combustion chamber. But a diesel fuel injection system has an assembly of many complex and intricate problems such as the desired rate of injection, secondary injection and injection pump etc., in addition to the atomization for ignition and combustion, the penetration and diestribution for proper utilization of air. The analysis is carried out by simplifing and modeling the injection phenomena and dividing into three parts comprising of fuel injection pump, high pressure pipe and fuel injection nozzle. The purpose of this paper is to describe an analytical simulation of the injection system and to speed up the work of developing injection systems for new engines. The effects of important injection parameters as predicted by the present model are found to be in good agreement with experiment. It can be seen that there is an optimal pipe diameter for maximum quantity injected.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.222-229
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• 2012

The cooling of a injector effects on the vapor pressure of cryogenic oxidizer spray, and it decides the phase transition point at the ignition process, when the combustion chamber pressure increases drastically. The phase transition of oxidizer spray affects the ignition characteristics, and several ignition tests with the LOx/$GCH_4$ uni-element coaxial swirl injector was performed in the different initial temperatures of oxidizer injector, in order to investigate the effect of injector cooling on the ignition transient characteristics. At the transition point of oxidizer phase, where the combustion chamber pressure increased over the LOx vapor pressure, the temporary quenching phenomenon of the flame occurred. The lower temperature of chilled down injector and tubing tends to move up the phase transition earlier.