• 제목/요약/키워드: combustion stability

검색결과 573건 처리시간 0.028초

모사 SNG 연료를 적용한 모델 가스터빈 연소기의 연소 불안정성에 관한 실험적 연구 (An Experimental Study on Combustion Instability in Model Gas Turbine Combustor using Simulated SNG Fuel)

  • 최인찬;이기만
    • 한국연소학회지
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    • 제20권1호
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    • pp.32-42
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    • 2015
  • The combustion instability was experimentally investigated in model gas turbine combustor with dual swirl burner. When such instability occurs, a strong coupling between pressure oscillation and unsteady heat release excites a self-sustained acoustic wave which results in a loud sound, and can even cause fatal damage to the combustor and entire system. In present study, to understand the combustion instability with a premixed mixture, the detailed periods of pressure and heat release data in unstable flame mode were investigated by various measurement methods at relatively rich condition and lean condition near flammable limits. Also, to prepare the utilization of synthetic natural gas (SNG) fuel in gas turbine system, an investigation was conducted using a simulated SNG including methane as a reference fuel to examine the effects of $H_2$ content on flame stability. These results provide that the instability due to flash-back behaviour like CIVB phenomenon occurred at rich condition, while the repetition of relighting and extinction caused the oscillation of lean condition near flammable limit. From the analysis of $H_2$ content effects, it is also confirmed that the instability frequency is proportional to the laminar burning velocity at both rich and lean condition.

소형 액체 로켓 엔진에서의 점화 시퀀스 결정 및 인젝터 수명 연장 기법 평가 (Determination of Ignition Squence and Estimation of Injector Life Extension Technique in Liquid Rocket Engine)

  • 박정;김용욱;김영한;문일윤;이재룡;강선일;정용갑;조남경;오승협
    • 한국연소학회지
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    • 제5권1호
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    • pp.43-53
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    • 2000
  • Experimental studies on determination of the supply leading time of propellants to combustion chamber have been made to stably and efficiently guarantee the ignition process with liquid rocket engine. The propellant used is a Jet A-1 as fuel and a liquid oxygen as oxidizer. Unlike impinging FOOF type of injectors are arranged radially and the designed O/F ratio is 2.34. The present experiment program also includes the stability on the quadlet type of ignitor using the triethylalumimum as an ignition source and injector life tests. Experimental results clarifies that the propellant supply through LOx leading to combustion chamber is proper for stable ignition and combustion processes based on the fuel and oxidizer manifold pressures, combustion chamber pressure, and the variation of flame length from the nozzle exit with lapse time, and shows that the leading supply time of propellants affects the engine performance little. The effect of positioning cooling holes is remarkable to protect the injector face.

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직분식 엔진에서 연료공급 조건에 따른 CNG와 공기의 혼합 및 연소특성 (Mixing and Combustion Characteristics of a CNG and Air according to Fuel Supply Conditions in a DI Engine)

  • 강정호;박종상;염정국;정성식;하종률
    • 한국분무공학회지
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    • 제13권1호
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    • pp.1-8
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    • 2008
  • It was investigated how fuel injection timing - early injection and later injection - in conjunction with throttle open rate effect the fuel-air mixing characteristics, Engine power, combustion stability and emission characteristics on a DI CNG spark Engine and control system that had been modified and designed according to the author's original idea. It was verified that the combustion characteristics were changed according to fuel injection timings and Engine conditions determined by different throttle open rates and rpm. It was found that the combustion characteristics greatly improved at the complete open throttle rate with an early injection timing and at the part throttle rate with a late injection timing. Combustion duration was governed by flame propagation duration in a late injection timing and by an early flame development duration in an early injection timing. As the result, we discovered that combustion duration is shortened, lean limit is improved, air-fuel mixing conditions controlled, and emissions reduced through control of fuel injection timing according to change of the throttle open rate.

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예혼합 희박 연소기의 연소특성에 관한 연구 (Study on the Combustion Characteristics of a Lean-Premixed Combustor)

  • 김한석;임암호;안국영;이상민
    • 한국연소학회지
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    • 제9권1호
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    • pp.25-31
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    • 2004
  • Various types of the air/fuel pre-mixer have been designed and tested to investigate the combustion characteristics of the lean-premixed gas turbine combustor, such as NO emission and flame stability. One type of the pre-mixers has been selected and installed to a 70 kW lean-premixed gas turbine combustor. The concentrations of CO and NO were measured with varying equivalence ratios in the combustion chamber at ambient pressure. The result shows that the emissions of CO and NO are heavily affected by the shape of the pre-mixer. The NO and CO emissions decreased, as the mixing ratio of air and fuel increased. In addition, the NO emission of the lean-premixed low NOx combustor is more dependent on the equivalence ratio than that of the conventional combustor.

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스파크점화기관에서 고속응답 FID를 이용한 실린더내 잔류가스량 측정에 관한 연구 (A Study for Measurements of In-Cylinder Residual Gas Fraction using Fast Response FID in an SI Engine)

  • 송해박;조한승;이종화;이귀영
    • 한국자동차공학회논문집
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    • 제6권1호
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    • pp.80-89
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    • 1998
  • The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

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과급 LPLi 엔진의 공연비 변화에 따른 출력성능 및 배기특성에 관한 연구 (The Study of Engine Output and Emission Characteristics according to Air Fuel Ratio far a Supercharged LPLi Engine)

  • 류재덕;윤용원;이기형;이창식
    • 한국자동차공학회논문집
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    • 제10권4호
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    • pp.77-84
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    • 2002
  • For the purpose of obtaining a fundamental data which is needed to develope the port injection type charged LPLi engine system, we manufactured intake port injection system of liquid charging LPG and modified heavy duty single cylinder LPLi engine from heavy duty diesel engine. Engine output and emission characteristics were analyzed under variable air/fuel ratio and charging pressure. Since LPG is consisted of propane and butane, we investigated combustion characteristics using this two kinds of fuel. From the result of charging engine performance test, engine torque increase about 30% ∼ 40% with 0.3bar charging pressure. In low speed condition, as charging pressure increase, combustion stability improve ill lean bum condition, but, in high speed condition, combustion stability make worse in lean bum condition. We know that engine output decreased rapidly from the condition of air excess ratio 1.3. In addition, we measured emission characteristics under the lean bum and charging condition. From this experiment, we found that CO emission is out of the question in the range from stiochiometric to lean burn and charging condition, but charging pressure has influence on HC emission.

연료 조성 및 스파크 플러그 위치 변경으로 인한 가스 엔진의 성능에 관한 연구 (Study on the Performance of an SI Gas Engine by Fuel Composition and Spark Plug Variation)

  • 김용래
    • 한국가스학회지
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    • 제18권6호
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    • pp.21-26
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    • 2014
  • 연료의 사용으로 인한 이산화탄소의 발생량을 줄일 수 있는 방법으로 바이오가스 또는 매립가스와 같은 신재생 가스 연료를 사용하는 방법이 도움이 될 수 있다. 그러나 다량의 불활성가스가 포함되어 있기 때문에 저발열량 및 연료 조성의 불균일함은 신재생 가스 연료를 발전용 엔진에 적용하는 경우, 엔진 성능에 큰 영향을 미칠 수 있기 때문에 이에 대한 연구가 필요하다. 본 연구에서는 신재생가스연료에 불활성가스가 엔진 연소가 불안정한 정도로 많이 포함된 경우에 수소 연료를 첨가함으로써 연소 안정성을 개선할 수 있음을 확인하고, 엔진의 열효율 및 배기 특성과 같은 성능 변화에 대하여 살펴보았다. 또한 같은 조건에서 엔진 효율 및 배기 성능을 향상시키기 위한 방안으로 길이가 긴 전극을 갖는 스파크 플러그를 적용하여 효과가 있음을 확인하였다.

압력변동이 연료 분사구에서의 당량비 변동에 미치는 영향에 관한 수치 해석 (Numerical Simulation of the Effect of Pressure Fluctuation on the Modulation of Equivalence Ratio at the Fuel Injection Hole)

  • 김현준;홍정구;신현동
    • 대한기계학회논문집B
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    • 제31권3호
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    • pp.292-299
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    • 2007
  • In gas turbine technology, the flame stability is inherently greater in conventional diffusion type combustion over a wider range fuel to oxidizer ratio. However, premixed type combustion which has narrow flame stability region, is widely used due to environmental reason. It has been observed in experiments that combustion instability of low frequency (${\sim}10Hz$) results from the modulation of equivalence ratio at fuel injection hole when a pressure fluctuation propagates upwards along the channel of the burner under an unchoked fuel flow condition. In this study, a commercial program was used to determine how the fuel flow rate changed with respect to the pressure, velocity of the fuel flow and the mass fraction in a choked and an unchoked condition. The calculation focuses on the upstream of the dump plane to know how the forced pressure with the fuel injection conditions affects the modulation of the equivalence ratio. Therefore, it is found that pressure fluctuation leads to oscillation of mass flow rate and then results in equivalence ratio modulation under the unchoked fuel flow condition.

SOFC/가스터빈 혼합발전을 위한 SOFC 생성물의 연소특성 (Combustion Characteristics of the SOFC Products for SOFC/Gas Turbine Hybrid Power Generation System)

  • 이병준;배철한
    • 한국연소학회지
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    • 제19권3호
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    • pp.44-52
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    • 2014
  • Solid oxide fuel cell(SOFC) makes electric power using hydrogen or reformed from methane and emits high temperature products that contain flammable species like hydrogen, carbon monoxide and methane which varies with operation condition. SOFC/gas turbine integrated system which uses thermal and chemical energy of the discharges is more efficient than SOFC itself. Burning character of the SOFC products will affect the efficiency and stability of the system. Experiments were conducted to know the characteristics of the flame for two typical composition of SOFC products, i.e. start-up and steady state composition. When coflowing air temperature was higher than $600^{\circ}C$, auto-ignitin occurred for both fuels. Though start-up fuel has higher contents of hydrogen, it makes longer flame than steady state composition. It was inferred that the amount of oxidizer necessary to burn makes this phenomenon. Steady state composition fuel was unstable since it contains lots of water. Nozzle that had 6 holes, distance between each hole was 16.7 times of hole diameter, improved the stability of the flame.

상호작용하는 메탄-수소 예혼합 대향류화염에 관한 연구 (A Study on Interacting $CH_4$-Air and $H_2/N_2$-Air Premixed Counterflow Flames)

  • 문창우;박정;권오붕;배대석;김정수
    • 한국연소학회지
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    • 제15권1호
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    • pp.38-42
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    • 2010
  • Using a counterflow burner, downstream interactions between $CH_4$-air and $H_2/N_2$-Air premixed flames with various equivalence ratios has been experimentally investigated. Flame stability maps on triple and twin flames are provided in terms of global strain rate and equivalence ratio. Lean and rich flammable limits are examined for methane/air and hydrogen/nitrogen/air mixtures over the entire range of mixture concentrations in the interacting flames. Results show that these flammable limits can be significantly modified in the presence of interaction such that mixture conditions beyond the flammability limit can be still burn if it is supported by stronger flame. The experiment also discusses various oscillatory instabilities in a stability map.