• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.1-8
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• 2012

An experimental study has been conducted to scrutinize into the influence of ultrasonic standing wave on the propagating behavior and structural stabilization of propane/air premixed flame at various equivalence ratios in half-open rectangular duct. Evolutionary features of the flame fronts are caught by high-speed images, and the variation of flame structure and local flame velocities along the propagation are analyzed. It is revealed that the propagation velocity agitated by the ultrasonic standing wave is greater than that without the agitation: the velocity enhancement diminishes as the equivalence ratio approaches the stoichiometric. Influence of standing wave on the flame overwhelms that of the buoyancy which slants the flame front towards top of the duct, and thus the standing wave contributes to the structural stabilization of propane/air premixed flame.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.44-51
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• 2017

An experimental results on the dynamic characteristics of hydrocarbon/air premixed flames with ultrasonic standing waves are presented and compared. Images of the propagating flames were acquired by using a high-speed camera, and the flame behavior of methane/air and propane/air premixed flame were closely scrutinized through the image post-processing. At the fuel-lean conditions, the flame propagation velocity increased due to the intervention of the ultrasonic standing wave and vice versa at the fuel-rich conditions.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.603-608
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• 2010

A study has been conducted experimentally to investigate behavior of ignition and flame spread over metal dust deposits with particle size using by a developed apparatus and thermogravimetric analysis(TGA). Zr, Ta and Mg-Al(90:10 wt%) alloy metal powders including Mg and Ti with different particle size were used. Also we used PMMA(Polymethylmethacrylate) powder to compare the combustion properties to those of metal powders. When dust layers were more than 5 mm in thickness, the dependency of deposit depth on flame spread rate over dust layer was not shown. With decreasing mean particle diameter, flame spread rate over Ti dust layer decreased, while the spread rate over Mg dust layer increased. For mean diameter of $51{\mu}m$, fire spread rate over pure Mg dust layer decreased to about 50 percent in Mg-Al(90:10 wt%) dust layer. The oxide thickness of metal dust used in this study tended to be inversely proportional with the spread rate, and it was quite small for influence with particle size. From the results of TGA for Ti and Mg, weight increasing curves(550 for Mg, 578 for Ta) were observed in the oxidation process, and they seems to be caused by ignition of upper dust layer.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.32-35
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• 2011

Experimental studies were carried out in an explosion chamber to investigate the influences of multiple cylinder obstacles on local flame propagation. The chamber dimension is 235 mm in height with a $1,000{\times}950\;mm^2$ rectangular cross section and a large vent area of $1,000{\times}320\;mm^2$. Multiple cylinder bars with obstruction ratio of 30% were used. In order to examine the interaction between the propagating flames and the obstacles, temporally resolved flame front images were recorded by a high speed video camera. The propagation behaviour of local flame fronts around the left obstacle was analyzed in terms of two different methods such as the incremental burnt area divided by the flame front length and the average of the local propagation velocity determined at each point along the flame front. It was found that two methods give good consistency.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.3
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• pp.58-67
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• 1984

공간적 화염전파에 대한 실험적인 파악을 통하여 오토엔진에서의 연소과정과 진행을 위한 깊은 통찰을 할 수 있다. 그것을 통하면 매우 희박한 공기, 연료 혼합기의 경우 실린더에서 직접소염 과정을 확인할 수도 있고 hydrocarbon의 불완전 연소와 나타나는 qunching zone간의 관계를 조사할 수도 있다. 광전도 섬유기술(Lichtleit-fasertechnik)을 사용하여 새로 개발된 측정방법을 이용하여 단기통 오토엔진에서 화염면의 공간적인 전파과정과 매우 희박한 공기 연료 혼합기 에서의 quench zone의 출현을 조사하였다. 측정결과들은 공기연료 혼합기가 희박해 질수록 화 염전파 과정이 점점 느려지는 것을 보여준다. 아주 높은 공기 과잉율을 갖는 엔진 운전에서는 화염속도와 연소속도가 매우 급하게 감소한다. 그리하여 화염면은 팽창 단계에서 상대적으로 증가하는 피스톤속도 때문에 더이상 피스톤을 따를 수가 없으며 그로 인해 직접 피스톤상부에 소염대가 형성된다. 그에 의해 배기가스에서의 hydrocarbon 방출의 급격한 증가와 효율이 급격히 감소하는 엔진 운전과 관련이 지어진다.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.67-75
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• 2019

The laminar burning velocity of endothermic fuel surrogates is measured in this study, in order to investigate combustion characteristics of aviation fuel after being used as coolant in an active cooling system of a hypersonic flight vehicle. A Bunsen burner was manufactured such that the laminar burning velocity can be taken for two types of surrogate fuels, SF-1 and 2. The results showed that the burning velocity of surrogate fuels was faster at high equivalence ratio conditions than that of the reference fuel (RF), and specifically, the velocity of SF-1 had the maximum value at the highest equivalence ratio compared with those of SF-2 and RF.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.4
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• pp.37-44
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• 2015

An experimental study was performed for the analysis of frequency-equivalence ratio correlation in the methane-air premixed flame influenced by ultrasonic standing wave. Evolutionary features of the propagating flame were caught by high-speed camera, and the variation of flame-behavior including local velocities was investigated in detail using a post-processing analysis of the high-speed images. It was found that propagation-velocity augmentation of the methane-air premixed flame by the intervention of ultrasonic standing wave was made in leaner mixture, but the velocity diminished when the strength of chemical reaction was saturated around the slightly fuel-rich side of stoichiometry.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.466-475
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• 2009

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of fuel injection velocity at the fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity, but its effect on the flame propagation velocity is not much greater under 4%. The increase of fuel injection velocity affects directly and linearly on the flame surface area in the fuel rich region and so enhances volume integral of reaction rate to accommodate the increment of fuel.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.44-51
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• 2005

The flame propagation velocity and the flame arrival time of methyl alcohol, which is widely used as a material of paint industry and organic synthesis, d mixing solvent, and an analytical reagent, were examined at different temperatures and concentrations. It was found that the smaller the vessel size, the easier and faster the combustion. The maximum combustion velocity was 200 cm/sec in the small vessel at $30^{\circ}C$. The flame arrival time was determined to be longer with larger vessels. and shorter with higher concentrations.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.13-18
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• 2013

Experimental studies were carried out to investigate the interactions between the propagating flame fronts and different multiple obstacles within an explosion chamber. The explosion chamber is 600 mm in height, $700{\times}700mm^2$ in cross-section and has a H/L value of 0.86. Three different multiple obstacles with the blockage ratio of 0.43 were replaced within the chamber. The results showed that relatively higher local flame displacement speed was observed with the triangular obstacle while the lower was observed with the circular one. It was found that the local flame displacement speeds behind the obstacle were largely dependent on the obstacle types. It was also found that as the flame interacted with the flow field generated behind the obstacle, the probability density functions(PDFs) of the local flame displacement speed were extensively distributed toward higher speeds.