• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.55-61
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• 2004

Numerical simulations were conducted in a rectangular scramjet combustor with a cavity and/or a step in order to investigate their performances for flame-holding. Flow structures and OH radical profiles in the cavity and the step were calculated. The calculated results showed that the cavity generated a larger recirculation zone than the step that had the same depth. Additionally, the combustor with a cavity could make a large low-velocity area than the combustor with a step. The cavity performance was determined by its depth and length. The cavities with too large or too short length did not work effectively, and a certain aspect ratio showed high performance for flame-holding. There was a minimal depth under which the cavity did not work as flame-holder. The fuel injections upstream the cavity and inside the cavity were also tested to investigate the effects on the cavity performance. The result showed that the fuel injection inside the cavity reduced reaction areas and residence time. Therefore, the upstream injection was preferable to the inside injection.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.590-593
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• 2009

To identify the detailed 3D flow characteristics of a model scramjet engine, a unified 3D numerical analysis was performed. The numerical domain of concern includes the entire flow path of the model scramjet engine extending from the intake to the nozzle exhaust. Turbulent models($k-{\omega}$ SST and low Reynolds number k-e with Sarkar model) were applied with comparison of experiment result. Intake side wall's effect on flow characteristics was analyzed in view points of flow quality at inlet duct and near the flame holder as well. The code is paralleled with multi-block feature using MPI(Massage Passing Interface) library to speed up the 3D calculation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.497-508
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• 1985

본 논문에서는 일양한 예혼합 기류중에 놓여진 원주 후류의 고온 순환류에 의 해 보지되는 난류 예혼합 화염을 대상으로 해서 유동의 가시화 및 온도와 이온전류의 변동의 측정에 의해서 화염의 구조를 조사한 결과, 원주 보염기 후류의 재순환 영역부 근에 형성된 전단층에 있어서는 코히렌트(Coherent)구조의 화염이 되고 하류부에서는 불규칙한 3차원 와(渦)에 지배되는 전파성 화염이 형성 되었다. 온도변동에 대한 쌍 봉성의 확율밀도분포와 이온전류변동에 대한 3개의 피이크의 확율밀도분포는 엷은 반 응면을 사이에 두고 미연혼합기괴와 기연가스괴가 서로 접하는 주름 상층류화염 또는 층류화염편의 구조에 대응하며, 코히렌트 와(渦)에 지배되는 화염에 있어서는 거시적 혼합은 코히렌트 와의 거동에 지배되나 그 구조는 주름상층류 화염과 일부 강한 전단 력을 받는 부분에는 분산 반응영역의 구조임이 밝혀졌다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1313-1314
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• 2006

For improvement of wear resistance property of atmospheric thermal plasma sprayed molybdenum (Mo) coating, diamond deposition on the atmospheric plasma sprayed molybdenum coating by the combustion flame chemical vapor deposition (CFCVD) has been operated. In this study, to diminish the thermal damage of the substrate during operation, a thermal insulator was equipped between substrate and water-cooled substrate holder. Consequently, diamond particles could be created on the Mo coating without fracture and peeling off. From these results, it was found that this process had a high potential in order to improve wear resistance of thermal sprayed coating.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2186-2191
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• 2008

An experimental study was performed to investigate the effect of swirl condition and secondary air rate on the Ion voltage and CO emission characteristics. In this study, the combustion characteristics were investigated with the variation of swirler diameter, vane angle, suction air rate. The result of this study, the Ion voltage increase with increasing the diameter of the swirler. Additionally with increasing the suction air rate, the Ion voltage is the same. The CO concentration depends on suction air rate. In the other hand, it is almost unaffected by swirler's diameter. The flame length and Ion voltage decease with decreasing O2 percentage of surrounding air.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.41-49
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• 2009

This paper present result of numerical simulation of premixed combustion around a triangle Bluff Body. And a numerical simulation of a premixed flame stabilization by a bluff body was performed using LES Model. The calculated results from the LES showed a good agreement with experiment data than k-model. Premixture combustion has flammability limit, quenching distance, smallest ignition energy has the combustion quality of the back. Bluff body makes a recirculation zone. Therefor velocity of behind bluff body is very slow. It was caused by slowly position speed and the fire occurred after the Bluff Body. Occurrence of fire it made the waste gas of high speed and the thrust made well.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1084-1093
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• 2010

Large eddy simulation of turbulent premixed flame stabilized by the bluff body is performed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic subgrid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.676-684
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• 1990

This study is on the pulsating combustion of premixed gas in a Rijke type combustor made of a honeycomb flame holder in a tube. Modelling for the onset condition of the oscillation is made by the ratio of the acoustic power generation based on the analysis of heat transfer to the power loss due to the thermoviscous dissipation and radiation. Experiment is performed for the characteristics of acoustic, thermal and combustion. It is shown that the theoretical modelling for the oscillation may be used as a limit condition. And the combustion analysis for the acoustic power generation is needed for better prediction of the onset condition. Experimental result shows that, by pulsation, the flame length is shortened and the flame temperature is decreased with increase in the heat transfer coefficient. The NO$_{x}$ concentration in the exhaust gas is significantly reduced by pulsation and the concentration of unburned hydrocarbon shows a little increase.e.

• Composites Research
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• v.27 no.4
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• pp.123-129
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• 2014

Ceramic matrix composites (CMCs) consist of such reinforcements as carbides, nitrides, borides and oxides, which have high melting points, low density, high modulus and high strength, for the purpose of increasing toughness. These materials are used for heat shielding systems for aerospace vehicles, high-temperature gas turbine combustion chambers, turbine blades, stator vane parts, etc. Oxide CMCs are used for the components of burner and flame holder and the high-temperature gas duct. CMCs are also applied to brake disks, which are subjected to severe thermal shock, and slide bearing parts under heavy loads. The research and development of the CMC are progressed for the strategic purpose in defense and energy industry; for instance, for aerospace applications in the U.S., and for hyper-speed aircraft, gas turbines, and atomic fissions in U.S., Japan, and Europe.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.395-399
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• 2009

Advanced afterburner used in the most modernized gas turbine has new designing paradigm to cope with reinforced power density. The most distinct change is the designing trend to integrate fuel injectors and flame holder in order to manage higher temperature of inlet air. F414 and F110-GE-132 engine adopted this methodology and installed a variable nozzle utilizing CMC(Ceramic Matric Composite) material and active cooling of nozzle flap with ejector nozzle in order to enhance the life cycle of engine components and an economical aspect. These technological trends can be utilized for an advanced ramjet engine and combined cycle engine like TBCC.