• 한국안전학회지
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• 제15권3호
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• pp.30-39
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• 2000

The present paper deals with the numerical simulation for the spray characteristics with swirling turbulent flows and dilution flows from swirl injectors in a simplified can type of gas turbine combustor. The main objective is to investigate the characteristics of swirling turbulent flows with dilution flows and to provide the qualitative results for the spray characteristics such as the droplet distribution and Sauter Mean Diameter(SMD). The gas-phase equations based on Eulerian approach were discretized by Finite Volume Method, together with SIMPLE algorithm and the Reynolds -Stress-Model. The liquid-phase equations based on Lagrangian method were used to predict the droplet behavior. The results of preliminary test are generally in good agreement with experimental data, and show that the anisotropy exists in the primary zone due to swirl velocity and injected air from primary injector, and then gradually decays due to turbulent mixing and consequently near-isotropy occurs in the region between primary and dilution zones. For the spray characteristics, it is indicated that the swirling flows of primary jet region increase the droplet atomization. In addition, it is showed that the swirling flows at the inlet region lead the air-fuel mixture to be distributed near the igniter and can significantly affect the spray behavior in the primary jet region.

• 한국가스학회지
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• 제24권4호
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• pp.25-31
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• 2020

산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 연소 특성을 이해하기 위하여 실험적 연구를 수행하였다. 노즐의 여러 연료 분사 방식에 대하여 NOx와 CO의 배출 특성, 화염 안정성 및 연소실 온도 분포에 대한 연소특성을 비교하였다. 주 연구 결과로는 연료홀 개수가 동일하고 연료 홀 직경이 감소하는 경우와 연료 홀면적이 동일하고 연료 홀 수가 감소되는 경우 연료의 연소용 공기층 침투가 커지기 때문에 NOx의 배출은 감소하지만 화염 안정성은 감소하게 된다. 그리고 동일 연료 홀 면적을 이용하는 분사방식에 있어서 연료 홀을 교차 변경하는 경우 연료의 평균 침투거리 증가로 NOx의 배출이 감소되며 연료 침투거리가 적은 연료가 화염을 안정화시키는 역할을 한다.

• 열처리공학회지
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• 제6권4호
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• pp.243-248
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• 1993

A Circulating Fluidized-Bed (CFB) with an internal nozzle and a partition wall was proposed. The technique of fluidization is related to operations first used commercially in the fields of metallurgical and mechanical engineering such as the heat treatment of metals and power station combustors. In the modified CFB, an internal nozzle and a partition wall were additionally set in the main bed. This cold mode CFB apparatus made of acrylic resin; the main bed is 1,500mm high and 100mm in the inner diameter, the internal nozzle is 130mm high and 10mm in the inner diameter, and the partition wall is 7mm thick and 100mm in the diameter. Glass beads of $89{\mu}m$ in the mean diameter were employed as bed materials.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.45-53
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• 2004

An experimental study was carried out to obtain the fundamental data about the effects of radicals induced injection on premixture combustion. A constant volume combustor divided to the sub-chamber and the main chamber was used. The volume of the sub-chamber is set up to occupy less than 1.5％ of that of whole combustion chamber. Radial twelve narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in the sub-chamber will derive the simultaneous multi-point ignition in the main chamber. While the equivalence ratio of pre-mixture in the main chamber and the sub-chamber is uniform. We have examined the effects of the sub-chamber volume, the diameter of passage hole, and the equivalence ratio on the combustion characteristics by means of burning pressure measurement and flame visualization. In the case of radical ignition method(RI), the overall turning time including the ignition delay became very short and the maximum burning pressure was slightly increased in comparison with those of the conventional spark ignition method(SI), that is, single chamber combustion without the sub-chamber. The combustible lean limit by RI method is extended to more ER=0.25 than that by SI method. Therefore the decrease of every emission including NOx and the improvement of fuel consumption is anticipated due to lean burn.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.235-241
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• 2006

Catalytic combustion is one of the suitable methods for micro power source due to high energy density and no flame quenching. Catalyst loading in the micro structured combustion chamber is one of the most important issues in the development of micro catalytic combustors. In this research, to coat catalyst on the chamber wall, two methods were investigated. First, $Al_2O_3$ was selected as a support of Pt and $Pt/Al_2O_3$ was synthesized through the alumina sol-gel procedure. To improve the coating thickness and adhesion between catalyst and substrate, heat resistant and water solvable organic-inorganic hybrid binder was used. Porous silicon was also investigated as a catalyst support for platinum. Through the parametric studies of current density and etching time, fabrication process of $1{\sim}2{\mu}m$ of diameter and about $25{\mu}m$ depth pores was confirmed. Coated substrates were test in the micro channel combustor which was fabricated by the wet etching and machining of SUS 304. Using $Pt/Al_2O_3$ coated substrate and Pt coated porous silicon substrate, conversion rate of fuel was over 95% for $H_2$/Air premixed gas.

• 한국추진공학회지
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• 제12권3호
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• pp.16-23
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• 2008

30 톤급 실물형 연소기의 산화제 매니폴드에서의 유동 균일성 문제를 파악하기 위하여 유동해석을 수행하였다. 분사기의 모사를 위하여 다공성 매질로 가정하고, 다공성도 (porosity)를 조절하여 분사기 차압을 모사하였다. 수직 및 수평 분리막에서의 구멍의 직경, 입구 포트의 형상에 따른 유동의 균일성 정도를 파악하고, 개선된 설계 수정안을 제시하였다. 수직 및 수평 분리막 구명의 형태와 배치 수정을 통하여 유량 균일성을 향상시킬 수 있음을 확인하였다.

• 한국연소학회지
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• 제11권2호
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• pp.7-14
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• 2006

Catalytic combustion is one of the suitable methods for micro power source due to high energy density and it can be applied to micro structured chamber without consideration of quenching since it is flameless combustion. Catalyst loading in the micro structured combustion chamber is one of the most important issues in the development of micro catalytic combustors. In this research, to coat catalyst on the chamber wall, two methods were investigated. First, $Al_2O_3$ was selected as a support of Pt and $Pt/Al_2O_3$ was synthesized through the alumina sol-gel procedure. To improve the coating thickness and adhesion between catalyst and substrate, heat resistant and water solvable organic-inorganic hybrid binder was used. Porous silicon was also investigated as a catalyst support for platinum. Through the parametric studies of current density and etching time, fabrication process of $1{\sim}2{\mu}m$ of diameter and about $25{\mu}m$ depth pores was confirmed. Coated substrates were test in the micro channel combustor which was fabricated by the wet etching and machining of SUS 304. Using $Pt/Al_2O_3$ coated substrate and Pt coated porous silicon substrate, conversion rate of fuel was over 95 % for $H_2/Air$ premixed gas.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.92-100
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• 2000

One method to analyse acoustic modes is proposed to predict the characteristics of acoustic instability in liquid rocket engine. It is based on the similarity between transverse acoustic modes and adopts two-dimensional axisymmetric geometry. Using this method, the first tangential mode in the prototype combustor can be analysed through the analysis of the first radial mode in the model combustor with doubled chamber diameter. Sample numerical calculation is demonstrated applying this method to sample rocket engine and thereby acoustic instabilities of the engine are investigated. The present results show a good agreement with the previous findings. The numerical analysis based on the proposed method is cost-effective and serves as the first approximation to the true solution.

• 설비공학논문집
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• 제2권2호
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• pp.112-118
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• 1990

Characteristics of heat transfer in a smooth and finned tube located vertically in atmospheric fluidized bed combustor which uses low grade anthracite coals was studied. Experiments to investigate the characteristics of heat transfer between smooth and finned tube are carried out and the results depend on particle size, fluidizing air velocity and bed temperature are summarized. It is found that heat transfer coefficient of the smooth and finned tube increases with decrease in particle diameter and increase in bed temperature. Furthermore, it is noted that heat transfer coefficient increase at the first with increase in the velocity of fluidizing air and tends to decrease at a certain fluidizing air velocity. The increase of heat transfer coefficient for the finned tube is appeared to be increased in 30% compared to that for the smooth tube.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.896-904
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• 2006

In a liquid rocket engine, the role of gas-liquid scheme injector as an acoustic resonator or absorber is studied experimentally for combustion stability by adopting linear acoustic test. The acoustic-pressure signals or responses from the chamber are monitored by acoustic amplitude. Acoustic behavior in a rocket combustor with a single injector is investigated and the acoustic-damping effect of the injector is evaluated for cold condition by the quantitative parameter of damping factor as a function of injector length. From the experimental data, it is found that the injector can play a significant role in acoustic damping when it is tuned finely. The optimum tuning-length of the injector to maximize the damping capacity is near half of a full wavelength of the first longitudinal overtone mode traveling in the injector with the acoustic frequency intended for damping in the chamber. When the injector has large diameter, the phenomenon of the mode split is observed near the optimum injector length and thereby, the acoustic-damping effect of the tuned injectors can be degraded.