• 대한기계학회논문집
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• 제16권3호
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• pp.578-588
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• 1992

본 연구에서는 작은 층류화염을 형성하는 소형의 연소기에 대해 화염의 안정 화를 위하여 선회가 가해지는 등축분류 층류제트 확사화염의 구조에 미치는 선회의 강 도, 연료와 공기의 출구 레이놀즈 수, 연료와 공기의 선회방향의 영향등을 이론적인 모델의 구성과 수치실험을 통하여 고찰한다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.165-172
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• 1999

Landfill gas has merely half heating value compared with liquified natural gas but can be greatly utilized as a commercial fuel. The authors have examined emission characteristics as well as measured burning velocity of LFG mixed gas which contains plenty of $CO_{2}$. With the viewpoint of fuel utilization, flame stability could be one of important characteristics of LFG. In this study, the comparison experiments are conducted between $CH_{4}$ and LFG for searching the region of flame stabilization based upon the flame blowout at maximum fuel stream velocity. As a result, it is found that stabilization region of LFG is not improved with that of $CH_{4}$ in non-swirl/or weak swirl jet diffusion flame. However, it is also known that flame stability is hardly affected by inert gas in the strong swirl with considering widened flame stabilization region of LFG rather than LNG.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.75-84
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• 2007

The effects of hydrogen enrichment to methane on NOx formation have been investigated with swirl stabilized pre-mixed hydrogen enriched methane flame in a laboratory-scale pre-mixed combustor(nominally of 5,000 kcal/hr). The hydrogen enriched methane fuel and air were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame stability was examined for different amount of hydrogen addition to the methane fuel, different combustion air flow rates and swirl strengths by comparing equivalence ratio at the lean flame limit. The hydrogen addition effects and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using gas analyzers, and OH chemiluminescence techniques to provide information about species concentration of emission gases and flowfield. The results of NOx and CO emissions were compared with a diffusion flame type combustor. The results show that the lean stability limit depends on the amount of hydrogen addition and the swirl intensity. The lean stability limit is extended by hydrogen addition, and is reduced for higher swirl intensity at lower equivalence ratio. The addition of hydrogen increases the NOx emission, however, this effect can be reduced by increasing either the excess air or swirl intensity. The NOx emission of hydrogen enriched methane premixed flame was lower than the corresponding diffusion flame under the fuel lean condition.

• 한국연소학회지
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• 제8권3호
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• pp.1-7
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• 2003

Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and by the high temperature flame. Flame figures, OH radical intensities, temperature distributions and emission concentrations were measured according to oxygen enriched concentration and swirl number in a turbulent diffusion flat flame. It appeared that flame figure became flat and NO concentration decreased with increase of swirl number, and that the flame temperature increased high with increase of oxygen enriched concentration. In particular, it was most significant between oxygen concentration $40{\sim}60%$.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.149-155
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• 2002

A promising new approach to achieve low pollutants emission and improvement of flame stabilities is tested experimentally using a hybrid cyclone jet combustor employing both premixed and diffusion combustion mode, Three kind of nozzles are used for LNG(Liquified Natural Gas) as a fuel. The combustor is operated by two method, One is ATI(Air Tangential Injection) mode, generated swirl flow by air as general swirl combustor, and the other is PTI(Premixed gas Tangential Injection) mode, The PTI mode consists of diffusion flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion flame. The results showed that the stable region of the PTI mode is more larger than the ATI mode. In addition, the reduction of NOx emission in PTI mode, as compared with that for the ATI mode is at least 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, the cyclone jet combustor has high performance of flame stability.

• 대한기계학회논문집B
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• 제28권2호
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• pp.146-153
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• 2004

A Promising new approach to achieve low pollutant emissions and improvement of flame stability is tested experimentally using a cyclone jet hybrid combustor employing both premixed and diffusion combustion mode. Three kinds of nozzle are tested for mixing enhancement of fuel and air. The LNG (Liquified Natural Gas) is used as a fuel. The combustor is operated by two methods. One is DC (Diffusion Combustion) mode generated swirl flow by air as general swirl combustor, and the other is HC (Hybrid Combustion) mode. The HC mode consists of diffusion jet flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion jet flame. The results showed that the flame stability of HC mode is significantly enhanced than that of DC mode through the change of mixing characteristics by modifications of fuel nozzle. In addition, the reductions of CO and NOx emission in HC mode, as compared with that for the DC mode, is large than about 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, it is identified that the cyclone jet hybrid combustor has the high performance of flame stability.

• 한국추진공학회지
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• 제23권1호
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• pp.1-8
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• 2019

스월/전단 동축형 인젝터를 통해 형성된 기체메탄-기체산소 확산화염의 동역학적 거동 및 구조분석을 위해 다양한 추진제 분사조건에 따른 연소실험이 수행되었다. 연구결과, 자발광 기법을 통해 가시화된 확산화염의 $OH^*$ 방사강도는 추진제 공급유량 및 운동량 플럭스 비 증가에 따라 높은 값을 나타내고 있으며, 스월을 가지는 화염은 그렇지 않은 것에 비해 더 우수한 반응성을 보였다.

• 대한기계학회논문집B
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• 제31권2호
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• pp.132-140
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• 2007

The temperature and soot of the visualized diesel engine's turbulent flow of the flame was measured qualitatively. In the combustion chamber, in order to judge the affect that the swirl current has on the current ratio two heads with different ratios were used. Using a high speed camera, the results were analyzed using flame visualization. In order to measure the temperature and soot of the turbulent flames like diesel flames, two color methods were used to acquire temperature and the soot of the flames according to the conditions through analyzing the two wavelengths of the flames. It was possible to measure the highest temperature of the non-swirl head visualized engine, which is approximately 2400K, and that swirl head engine managed up to 2100K. With respect to the visualized diesel engine soot, we got the grasp of the KL factor which bears the qualitative information of the soot. This study is dedicated to suggesting the possibility of measuring not only the temperature but also soot of the diffusion flame of the diesel engine turbulent flames.

• 한국추진공학회지
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• 제21권2호
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• pp.1-8
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• 2017

본 연구에서는 모델연소실 내부 메탄-산소 확산화염의 연소특성을 분석하기 위해 추진제의 다양한 분사조건에서 연소실험을 수행하여 연소안정한계 측정 및 화염의 형상변이를 관찰하였다. 연구 결과, 추진제가 이론당량비 조건으로 접근할수록 높은 산소 Reynolds 수($Re_o$) 구간에서도 안정적인 부상화염이 관찰되었으며, 가시화염의 길이는 증가하고, 부상높이는 감소하는 경향이 나타났다. 스월 동축형 인젝터에 의한 추진제의 스월효과로 인해 폭이 넓고, 길이가 짧은 화염이 생성되어 연소실 크기가 제한적인 추력기에서의 사용이 적합함을 확인하였다.

• 에너지공학
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• 제11권4호
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• pp.350-358
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• 2002

The present work determined the flame structure characteristics of coal syngas combusted inside swirl burners with various nozzle types. Fuel nozzle types are largely classified into two groups of axial and tangential. Experiments were carried out for investigating the effects of fuel nozzle geometry, fuel composition ratio, heating rate, excess air, and degree of swirl on the turbulent diffusion flame structure. To determine the characteristics of the flame structure, axial type fuel nozzle diameter of laboratory-scale combustor is varied to 1.23, 1.96, and 2.95 ㎜ and the direction of tangential type nozzles are varied to radial, clockwise, and counter-clockwise. The comparison of the experimental results was performed to understand functional parameters relating the flame structure. Data analysis showed that the vertical straight flame height generally decreased with increasing swirl number and decreasing axial type nozzle diameter. Flame height established with tangential type nozzle is 3 times shorter than that with vertical type. The flame structures among the 3 different tangential fuel nozzles relatively showed no particular difference. By increasing the heating rate, the width of flame increased generally in both vertical and tangential flame. Within the present experimental parameters of the investigation, flame structure is mainly depends on the nozzle type of the combustor. The visually investigated flame lengths are confirmed through the analysis of temperature profile of each flame.