• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.30-40
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• 1995

Optically accessible D. I. diesel engine with a rectangular combustion chamber was constructed to visualize the behaviors of sprays and flames in the combustion camber with the close conditions of pressure and temperature in an actual engine. The behaviors of sprays and flames in the combustion chamber as the operating conditions of this engine were photographed with high speed camera by Diffused Background Illumination Method. With photographs taken by this method, behavior of spray droplets injected into the combustion chamber, ignition points, and flame propagation were observed and analyzed at a time-and space-dependent fashion.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.624-631
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• 1996

This study describes extinguishment mechanism of the purely buoyant diffusion flame using the water spray. Experiments are systematically carried out for the oul pool fire with the six different atomizing nozzles. From the measurement of burning rate which represents the combustion intensity of fire, it is observed that the water spray is able to act to enhance fire rather than to extinguish fire. The air entertainment due to the water spray is visualized to understand this phenomenon, acting to enhance fire. In order to observe effects of droplet size on fire extinguishment, and amount of water which reaches the flame base, fuel surface, and mean diameter of droplets are measured. When water droplets are too small, they do not reach the flame base because they can the water spray having too small doplets is ineffective for extinguishment of the oil fire.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.24-30
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• 2003

This paper presents the characteristics of lifted height and flame length from non-premixed jet flames in highly preheated air to investigate the detail combustion mechanism in the gas turbine or HCCI engine, etc. Special attention was paid to the effect of preheated air temperature, oxygen concentration and fuel injection flow rate on flame length and lifted hight. By using highly preheated air, stable flames were formed even in low oxygen concentration condition. The lifted height increased with decreasing preheated air temperature, where the flame length showed opposed phenomena. The flamelet model, which is thought to have very thin flamelet, is difficult to applicable to the present flame conditions which is formed In low oxygen concentration in highly preheated air.

• Journal of ILASS-Korea
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• v.26 no.3
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• pp.142-148
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• 2021

The objective of this study is to analyze the basic flame behavior characteristics using the single fuel droplet combustion of diesel, palm-based biodiesel, and canola-based biodiesel. The results were compared and analyzed through the post processed image, which was applied the threshold level for removing noise in the raw image. The raw image was taken by a high-speed camera during the entire combustion process. At the same time, the maximum flame length, which was measured by the application code of the MATLAB program, the ignition delay, and the combustion period were compared and analyzed.

• Journal of ILASS-Korea
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• v.2 no.4
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• pp.36-46
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• 1997

The present study investigated the effects of MTV(Manifold Throttle Valve) on the fuel distribution and the flame stability in a SI engine at cold, idling condition. For the quantitative measurement of fuel distribution with PLIF method, compensating techniques of various factors such as laser beam nonuniformity, background image and local OTF nonuniformity were developed. As a result, it was found that MTV had a positive effect on the air-fuel mixing and flame stability.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.356-359
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• 2012

SNCR 기술은 SCR에 비해 탈질 효율은 떨어지지만 촉매없이 고온 배출가스에 NH3 또는 요소수를 직접 분사하여 질소와 물로 환원시키는 방법이므로 초기 투자비 및 운영비가 적어 최근 국내 대다수의 소각장, 산업용 보일러 등에 널리 적용되고 있다. 단, SNCR 기술은 급격한 온도 강하나 접근의 불용이성, 불균일한 혼합, 액적의 증발시간 지연, 불균일한 운전 조건 등의 영향을 크게 받으며, 특히 반응 온도가 가장 중요한 변수로서 최적 반응 온도 영역대가 약 800~$1,000^{\circ}C$라는 점에서 이상적인 반응 온도 조건을 찾아서 환원제를 분무하는 것이 매우 중요하다. 이에 본 연구에서는 열유동 전산해석을 통해 스토커식 소각로의 폐기물 성상별 화염 온도 분포를 예측하고 적정 반응 온도 영역을 확인하여 요소수 주입 고도를 선정, 폐기물 성상별 분무 조건을 확립하고자 수치 해석적 연구를 수행하였다. 폐기물 성상(고질/중질/저질 폐기물)별로 화염 온도를 예측한 결과, 최적 반응 온도 영역대가 약 800~$1,000^{\circ}C$, 폐기물 성상의 심한 변화 때문에 소각로의 효율적인 연소 조건 제어에 어려움 등을 고려하여 약 700~$1,000^{\circ}C$ 온도 영역대를 환원제 분무 온도로 선정하였다. 폐기물별로 발열량에 따른 화염 온도가 모두 다르기 때문에 환원제 분무 위치를 3지점으로 선정하여 각 지점별로 분무 운전 조건을 확립하였다.

• Fire Science and Engineering
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• v.22 no.3
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• pp.221-227
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• 2008

In this study, the fire suppression characteristics of a water mist with natural wind in a road tunnel were calculated using the FDS(Fire Dynamic Simulation) code. In addition, the cooling and the chemical kinetic effects of water vapor on fire extinction ere investigated in a counterflow non-premixed flame using a detailed chemistry. As a result, the behavior of fire plume and the spray characteristics of water mist are modified remarkably with the increasing of wind velocity. In the case which is not the external natural wind, small droplets are more efficient in fire suppression than large droplets. However, the large droplets show better results on the fire suppression than the small droplets with the increasing of wind velocity. It can be estimated that the natural wind disturb the penetration of water droplets into the flame region and decrease the effect of oxygen dilution. Finally, it can be identified that the fire into the natural wind can be suppressed with smaller amount of $H_2O$ by flame stretching effect in the flame region than one in an enclosure, and the chemical kinetic effects of $H_2O$ on fire extinction are not affected significantly the velocity of natural wind.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.53-60
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• 2020

In liquid-fuel spray combustion, an experimental study was conducted to observe the effect of ultrasonic excitation on the ultrasonically-atomized liquid fuel flame by controlling pressure field through an ultrasonic standing wave. Flame of the ultrasonically-atomized kerosene aerosol was visualized by using a high speed camera, DSLR, and Schlieren photography. The amount of fuel consumed was obtained by a precise flow-rate measurement technique during combustion, through which the ratio of carrier gas (air) to fuel mass was able to be obtained, too. As a result, it could be found that the combustion reaction-rate of the liquid-fuel aerosol was increased by applying an ultrasonic standing wave to the secondary flame zone of the flame.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.43-49
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• 1998

In order to clarify the effect of equivalence ratio and kinds of fule in flame structure, a numerical simulation of triple flame developed in a co-flowing methane-air and air stream was carried out by the elementary chemical reaction mechanism. The following conclusions were obtained. Equivalence ratio at which the apparent burning velocity is maximum is a little larger than that of the one-dimensional premixed flame. Apparent burning velocities are two times higher than that of the one-dimensional premixed flame for the methane-air. The flame thrusts out forward in the downstream of the boundary between mixture and air stream, and a part of the flow is bent and forks out in this protruding flame so that a triple flame is originated; this triple flame is composed of fuel rich and lean premixed flame branches and a diffusion flame branch. Near the equivalence ratio at which the burning velocity of rule-dimensional premixed flame is the largest the effect of one-dimensional premixed flame becomes large and the fuel rich premixed flame advances and becomes vertical to the flow direction.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.242-246
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• 2004

Nano-sized a-alumina with a narrow distribution was prepared by using Flame Spray Pyrolysis (FSP). The microemulsion of water in oil (W/O) was prepared to make ultrafine droplets for FSP process. Kerosene (fuel) as a continuos phase and Al(NO$_3$)$_3$$.$9$H_2O$ (oxidizer) aqueous solution as a dispersed phase were prepared for microemulsification. The microemulsion with dispersion stability was obtained by adjusting the composition of 80 vol% kerosene, 10 vol% aqueous solution, and 10 vol% emulsifying agent. Microemulsion was sprayed onto the flame by using two-fluid nozzle spray gun under the condition of 0.03 ㎫ air pressure. The synthesized products were $\alpha$-alumina phase with the size of 20 to 30 nm.