• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4671-4676
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• 2010

This study is intended to understand flame behavior of the pool fire by height of fire source. Liquid fuels were methanol and n-Heptane which are used in many studies of pool fire. Size of vessel was $100mm{\times}100mm{\times}50mm$ and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics of pool fire was decreased according to increase of height of fire source because entrainment volume of relative cold air was increased from the outside to flame.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.87-94
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• 2014

It becomes critical to understand an energy coupling mechanism between flow perturbations and combustion heat release rate fluctuations for the understanding of high-frequency combustion instabilities occurring in high-performance combustion/propulsion systems. A significant amount of experimental researches have been carried out to understand flame dynamic characteristics by use of flame transfer functions with artificial flow disturbances. Among them, there exist substantial studies on flame response by the excitation of inlet flow. Recently, experimental studies simulating transversal modes excited in actual combustion systems are under way.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.33-42
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• 2014

Flame behaviors and interaction between pilot and main flames in a dual swirl combustor were investigated experimentally and numerically. Under the condition of fixed swirl angle of $45^{\circ}$ for main flame, the swirl angle of pilot flame, total heat release rate and equivalence ratio of main flame were used as major parameters. As a result, detailed flame stability diagram of dual swirl combustor was identified in terms of 5 flame modes with the changes in total heat release rate and equivalence ratio of main flame. It was found that the swirl angle of pilot flame plays the most important role in the changes in flame location and overall flow structure inside the combustor, and thus leads to the significant change in the interaction between pilot and main flame.

• Journal of Energy Engineering
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• v.10 no.2
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• pp.153-160
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• 2001

본 연구에서는 고온 분위기 온도 및 대기압 하에서 액적의 급속가열과 연소가 가능한 고온 연소로 장치와 고속도 비디오 카메라를 이용하여 다조성 단일 액적 연소에 대해 고찰하였다. 그 결과 저비점 성분을 혼합한 경유의 액적은 기본적으로 입경의 2승 법칙에 의해서 감소되었으며, 그 과정에서 입경이 일시적으로 급속히 감소하는 현상이 보여짐과 더불어 연소기간도 단축되었다. 즉, 저비점 성분을 혼합한 경유의 액적은 미세폭발 현상에 의해 기존 디젤 연료에 비해 더 빨리 증발되고 연소가 되었다. 또한, 순수 파라핀계 및 함산소계 연료의 화염은 전체 연소기간동안 기존 경유의 화염에 비해 푸른색을 띠고 있어, 매연이 없는 연소를 입증해 주었다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.164-171
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• 2006

The results of an experimental investigation into the breakdown characteristics of a model power line in the presence of oil flame are reported under the application of 60[Hz] ac and dc high-voltages. It is appeared that flame can reduce by more than half, 80[%] in maximum, the breakdown voltage with the case of h=0 under ac and dc applications. Taking a horizontal model line with a k=0.5 of flame position, it can be seen from the results that the reduction of flashover levels, in comparison with the no-flame case, are 78.6[%] for h=0[cm], 59.7[%] for h=3[cm], 46.9[%] for h=6[cm], 41.5[%] for h=9[cm] and 35.4[%] for h=12[cm] when ac voltage is applied.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.763-768
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• 2011

The effects of $CO_2$-dilution on combustion instability were studied in order to apply biogas in a dual lean premixed gas turbine combustor on a real-scale dual lean premixed burner head which is originally developed for Natural Gas fuel. Combustion instability is reduced by $CO_2$ dilution effect according to the result of dynamic pressure signal and phase-resolved $OH^*$ images. The reason for this is that dilution of $CO_2$ reduces heat release perturbation and increases flame volume due to reduction of the flame speed and expansion of flame surface.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.41-48
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• 2017

The combustion characteristics of gaseous methane-gaseous oxygen, an eco-friendly bipropellant injected by shear coaxial injector, were investigated. Flame was photographed under various combustion conditions using a DSLR camera, and the characteristics of the flame shape was quantified by image post-processing. From the view point of stabilization, the diffusion flame could be divided into anchored flame regime and blow-off regime. As the oxidizer Reynolds number ($Re_o$) increased, a probability of the formation of anchored flame increased with the length of flame. The shear coaxial injector used in this experiment was found to require a large length-to-diameter ratio of combustion chamber because it formed a relatively long flame in the injection direction due to a poor mixing depending only on the momentum diffusion of two propellant jets.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1633-1639
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• 1993

In spark ignition engine, EGR of lean mixture operation has advantage in emission, but disadvantages in power output and combustion flame propagation. Fast burn system is known to be a useful method to solve these disadvantages. This paper presents the characteristics of in-cylinder flow for different combustion chamber geometries, and the correlation between the in-cylinder flow and the combustion flame speed using an ion current method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.379-385
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• 2010

Mechanism of combustion frequencies occurring during combustion is experimentally investigated in a model combustor with V-gutter flameholder. The combustor has a long duct shape with a cross section area of $40{\times}40mm$. The v-gutter type flameholder with 10, 12, 14mm width is mounted at the side wall of combustor. CNG were used as fuel, and the fuel was injected transversely into air crossflow. It is found that combustion frequencies were considered as first longitudinal mode caused by combustor geometry. And it is found that flameholder length affects the flame holding range. Also, it is observed first longitudinal pressure oscillations make significant changes of flame structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.303-306
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• 2011

An experimental study has been conducted to investigate the effects of an ultrasonic standing-wave field to the behavior of methane/air premixed flame. Visualization technique utilizing the schlieren method was employed for the observation of premixed flame behavior. The shape of flame front and local flame velocity were measured according to the variation of reactants pressure and chamber opening/closing condition. The flame front was distorted and severely deformed to a lotus-type flame by the interaction of ultrasonic standing-wave and the reflection wave coming from an end wall of reactor.