• 한국분무공학회지
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• 제23권1호
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• pp.16-21
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• 2018

The current study has developed an in-house 3D FEM code in order to model thermoacoustic problems in a gas turbine combustion system and compared calculation results of main instability characteristics with measured ones from a lab-scale partially-premixed combustor. From the comparison of calculation results with the measured data, the current model could successfully capture the harmonic longitudinal instability frequencies and their spatial distributions of the acoustic field as well as the growth rate of self-excited modes.

• 대한기계학회논문집B
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• 제37권1호
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• pp.51-57
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• 2013

본 연구에서는 가스터빈 연소기에 적용하기 위한 예혼합 스월버너의 배기가스 및 화염안정성 최적화를 위하여 버너의 구조변경에 따른 연소특성을 실험적으로 분석하였다. 버너의 연료분사구조에 따른 배기가스 배출 특성을 파악하고자 단일연료분사구조와 이중연료분사구조를 갖는 예혼합 버너의 연소특성을 비교 분석하였으며 이중연료분사구조 적용 시 연료/공기 혼합특성이 향상되어 CO와 NOx의 배출농도가 감소하는 경향을 나타내었다. 또한, 노즐출구와 라이너의 지름 비(confined ratio)에 따른 연소부하 및 배기가스 특성을 분석한 결과 confined ratio 감소 시 연소부하 감소로 인해 NOx 배출농도가 감소되었으며, 체류시간의 증가로 인해 CO의 산화 반응이 증가하여 CO 배출농도가 감소하였다. 노즐분출속도는 30 m/s에서 배기가스특성이 우수하며, 속도 증가(40 m/s) 시 배가스특성이 저하되고 속도 감소(20 m/s) 시 화염안정성이 저하되었다.

• 한국분무공학회지
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• 제27권1호
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• pp.18-25
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• 2022

Hot-firing tests were performed to experimentally confirm the effect of the eigenmode in the fuel-air mixing section on combustion instability by changing mixing section length, inlet mean velocity, equivalence ratio, and swirler geometry. A premixed gas composed of air and ethylene was supplied to the combustion chamber through an mixing section and an axial swirler. As the mixing section length increased, the inlet velocity perturbation decreased, but the combustion instability increased more. It was found that the resonance frequency of the first longitudinal mode in the mixing section shifted to the third longitudinal mode as the length of the mixing section increased. The results implied that the transition of the resonace frquency by changing the length of the mixing section might cause combustion instability.

• 대한기계학회논문집
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• 제11권1호
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• pp.145-153
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• 1987

본 논문에서는 예혼합동축분류화염에 있어서 재순환역 안으로의 기체(공기, 연료, 혼합기) 주입과 2차공기의 족회가 화염안정성, 화염형상 및 재순환역에 미치는 영향을 명확히 하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.475-481
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• 2004

Recently it is strongly required on lower fuel consumption. lower exhaust emission, higher engine performance. and social demands in a spark ignition gasoline engine. In this study. the experimental engine used at test. it has been modified the lean burn gasoline engine. and used the programmable engine management system, and connected the controller circuit which is designed for the engine control. At the parametric study of the engine experiment, it has been controlled with fuel injection, ignition timing. swirl mode, equivalence ratio engine dynamometer load and speed as the important factors governing the engine performance adaptively. It has been found the combustion characteristics to overcome the hysteresis phenomena between normal and lean air-fuel mixing ranges. by mean of the look-up table set up the mapping values. at the optimum conditions during the engine operation. As the result, it is found that the strength of the swirl flow with the variation of engine speed and load is effective on combustion characteristics to reduce the bandwidth of the hysteresis regions. The results show that mass fraction burned and heat release rate pattern with crank angle are reduced much rather, and brake specific fuel consumption is also reduced simultaneously.

• 에너지공학
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• 제13권4호
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• pp.311-318
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• 2004

본 연구에서는 정적연소실을 이용하여 차량용 대체연료로써 메란 및 수소첨가 메탄의 연소특성을 수소첨가율, 점화위치 및 점화방법에 따라 고찰하였다. 그 결과, 중심점화이고 수소를 첨가하지 많은 순수 메탄의 화염전파과정은 타원형으로 전파하나 수소첨가율이 증가함에 따라 화염면상에 매우 규칙적인 세포구조를 가진 불안정한 타원형화염으로 천이되었고 연소속도도 증가하였다. 또한, 벽면 및 0.5R 점화이고 수소를 첨가하지 않은 순수 메탄의 화염전파과정은 불안정한 타원형으로 전파하고 있었지만, 수소첨가율이 증가함에 따라 연소중기에 불안정한 타원형에서 평면형으로 천이 됐다가 연소말기에는 화염면 선단이 움푹 패인 매우 불규칙한 세포구조를 갖는 패기형으로 변화되었으며 연소속도도 증가하였다 한편, 세 가지 점화위치 모두에 있어서 MSCDI와 CDI사용에 따른 화염전파형태는 외견상 큰 차이는 없었지만, 동일시간에 MSCDI장치의 화염면적은 CDI의 화염면적보다 약간 더 크게 나타났다.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.129-139
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• 1995

This study investigates the combustion characteristics of methane-hydrogen-air premixture in a constant volume combustion chamber. Primary factors of the combustion characteristics of methane- hydrogen-air premixture are the equivalence ratio and hydrogen supplement rate. In the case of $\phi$= 1.1, maximum combustion pressure and heat release rate have peaks, and they increase as the initial pressure and hydrogen supplement rate increase. The total burning time is also the shortest at the $\phi$= 1.1, it shorten by lowering the initial pressure and by increasing the hydrogen supplement rate. The maximum flame temperature is shown at the $\phi$= 1.0, and increasing the initial pressure and hydrogen supplement rate, it increases. The concentration of NO reveals the highest value at the $\phi$= 0.9, and it increases by increasing the initial pressure and hydrogen supplement rate. It is also found that the limit of lean inflammability of methane-hydrogen-air premixture is greatly widened by increasing the hydrogen supplement rate.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.65-75
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The results indicated that even the vety lean mixture, which is normally not flammable in single chamber type, could be burned within. a comparatively short time by using sub-chamber with stratified charge method. And the lean inflammability limit of mixture in a main chamber was about ($\phi_m$cr=O.46, when the equivalence ratio of a sub-chamber was $\phi_s$= 1.0. Initial time of pressure increase and total burning times were decreased and maximum combustion pressure. was increased as the equivalence ratio of both sub and main chamber approached unity. Specifically, initial time of pressure increase and total burning times were greatly affected rather by. the equivalence ratio of sub-chamber than that of main chamber. The maximum combustion pressure was little affected if the total equivalence ratio lies in the same range.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.8-16
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• 1999

In this study, a new type of laser-induced ignition using a conical cavity has been developed to utilize all the available incident laser energy. In the method, it is possibile to ignite combustible methane/air mixtures by directing a laser beam of a constant small diameter into a small conical cavity, without focusing the laser beam. Shadow graphs for the early stage of combustion process show that a hot gas jet is ejected from the cavity, especially with lean mixture. After a very show time, the hot gas jet finishes issuing and the flame behavior is quite similar to flame propagation initiated by a conventional spark ignition. The combustion process using the new method exhibits more rapid pressure increase and a higher maximum pressure rise than that of the center ignition using laser-induced spark, with significant decrease in the combustion time. Also, the new ignition method is numerically modeled to simulate the flame kernel development and subsequent combustion process using the KIVA-IIcode. The calculated results show satisfactory agreement with experimental results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.71-74
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• 2007

희박 예혼합 스월 연소기의 난류 연소와 화학반응간의 간섭 메커니즘을 파악하기 위하여 Large Eddy Simulation(LES)을 수행하였다. 난류 화염의 유동 특성을 자세히 살펴보기 위하여 비정상 난류 연소 수치해석 기법을 적용하여, 약간의 연료 덩어리가 일차연소영역(Primary combustion zone)에서 빠져나와 선회 방향으로 흘러 국부적 핫스팟(hot spot)을 발생시키며, 이는 large vortical structure를 만들어 내는 것을 관찰 할 수 있었다. 압력변동과 비정상 열 방출 사이의 관계는 공간 및 시간적 Rayleigh parameter에 의해 고찰되었다.