• Title/Summary/Keyword: Flame Propagation Process

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The Experimental study on the Flame Propagation Process of a Constant Volume Combustion Chamber (정적 연소실내에서 화염 전파 과정에 대한 실험적 연구)

  • Kim, Chun-Jung;Kang, Kyung-Koo
    • Journal of the Korean Society of Industry Convergence
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    • v.2 no.1
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    • pp.121-130
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    • 1999
  • It is necessary to measure pressure, temperature, chemical equilibrium and the shape of flame in order to understand the combustion process in a combustion chamber. In particular, the flame formulation and combustion process of divided combustion chamber are different from those of a single chamber, And the variable diameter of a jet hole can effect not only physical properties like ejection velocity, temperature and time of combustion but also a chemical property like the reaction mechanism. Accordingly temperature is one of the most important factors which influence the combustion mechanism. This paper observed shape of flame by using the schlieren photographs and measured the pressure in a combustion chamber and the reaching time of the flame by ion probe By doing these, we investigation the formulation of the flame and the process of propagation. These measurement methods can be advanced in understanding the combustion process and process and propagation of flame.

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Flame Propagation Characteristics of Propane-Air Premixed Mixtures (프로판-공기 예혼합기의 화염전파 과정에 관한 연구)

  • Bae, Choong-Sik
    • Journal of the Korean Society of Combustion
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    • v.1 no.2
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    • pp.21-29
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    • 1996
  • Flame propagation characteristics of propane-air mixtures were experimentally investigated in constant-volume combustion chambers. Flame propagation process was observed as a function of mixture strength, initial mixture temperature and initial mixture pressure in quiescent mixtures. A cylindrical combustion chamber and a spherical combustion chamber contain a pair of parallel windows through which optical access into the chamber can be provided. Laser two beam deflection method was adopted to measure the local flame propagation, which gave information on the flame size and flame propagation speed. Pressure development was also measured by a piezoelectric pressure transducer to characterize combustion in quiescent mixtures. Burning velocity was calculated from flame propagation and pressure measurements. The effect of flow on flame propagation was also investigated under flowing mixture conditions. Laser two beam method was found to be feasible in measuring flame propagation of quiescent mixtures. Flame was observed to propagate faster with higher initial mixture temperature and lower initial pressure. Combustion duration was shortened in the highly turbulent flowing mixtures.

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Study on the Turbulent Edge Propagation Speed of a Lifted Diffusion Flame in Turbulent Mixing Layer (난류 혼합층 확산화염에서 부상선단의 난류전파속도에 대한 연구)

  • Kim, Jun-Hong;Chung, S.H.;Ahn, K.Y.;Kim, J.S.
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.55-61
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    • 2004
  • Leading front of a lifted diffusion flame in turbulent mixing layer was investigated in order to find a appropriate definition of the turbulent edge propagation speed. The turbulent lifted diffusion flame was simulated by employing the flame hole dynamics combined with level-set method which yields a temporally evolving turbulent extinction process. By tracing the leading front locations of the temporal flame edges, temporal variations of the liftoff height, local flow velocity, and edge propagation speed at the leading front were investigated and they demonstrated the flame-stabilization condition of the turbulent lifted flame. Finally, a turbulent edge propagation speed was defined and its temporal variation from the simulation was discussed.

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Propagation Speed Characteristics of Premixed Methane-Air Flame in a Combustion Chamber with Model of Engine Cylinder (엔진실린더 모형 연소실내의 메탄-공기 예혼합기의 화염전파속도 특성)

  • 전충환
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.2
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    • pp.225-231
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    • 1998
  • Flame propagation speed characteristics of methante-air mixtures were experimentally investigated in combustion chamber modelled engine. Flame propagation process was known as a funtion of equivalence ratio initial pressure and initial temperature. Ion probe and schlieren photograph were applied to measure the local flame speed and flame radius in quiescent mixtures. Pressure was also measured to make sure of the reproducibility and to apply combustion analysis. Burning velocity was calculated from the flame propagation speed and combustion analysis. Flames were developed faster with higher initial pressure and initial temperature but showed maximum propagation speed at equivalence ratio 1.1 regardless of initial pressure and temperature. Local flame speed was maximum values at near midpoint between center and wall.

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A Study on the Flame Configuration and Flame Stability Mechanism with a Nozzle Diameter of Laminar Lifted Jet Flame (층류제트 화염의 노즐직경에 따른 안정화 메커니즘과 화염형상에 관한 연구)

  • Kim, Tae-Kwon;Kim, Kyung-Ho;Ha, Ji-Soo
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.2
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    • pp.204-215
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    • 2011
  • Flame stability is the one of the main mechanism of laminar lifted flame and flame propagation velocity becomes a yardstick to measure the flame stability. Bilge has presented the flame propagation velocity of the triple flame and the flame stability mechanism related the flame configuration and mixture fraction. However, there was not able to observe all process of flame ignition and extinction for small nozzle diameter. In this paper, we have subdivided the flame configuration and stability mechanism and classified the flame behavior with a nozzle diameter. Also we have subdivided the 'triple flame propagation opened' and the 'triple flame propagation closed' from the triple flame propagation of triple flame criterion.

Combustion Characteristics Using a S.I. Optically Acessible Engine with SCV (SCV를 장착학 가솔린 가시화엔진에서의 연소특성)

  • 정구섭;김형준;전충환;장영준
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.1
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    • pp.115-123
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    • 2001
  • This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

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Simulation of a Diffusion Flame in Turbulent Mixing Layer by the Flame Hole Dynamics Model with Level-Set Method (Level-Set 방법이 적용된 Flame Hole Dynamics 모델을 통한 난류 혼합층 확산화염 모사)

  • Kim, Jun-Hong;Chung, S.H.;Ahn, K.Y.;Kim, J.S.
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.102-111
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    • 2004
  • Partial quenching structure of turbulent diffusion flames in a turbulent mixing layer is investigated by the method of flame hole dynamics to develope a prediction model for the turbulent lift off. The present study is specifically aimed to remedy the problem of the stiff transition of the conditioned partial burning probability across the crossover condition by adopting level-set method which describes propagating or retreating flame front with specified propagation speed. In light of the level-set simulations with two model problems for the propagation speed, the stabilizing conditions for a turbulent lifted flame are suggested. The flame hole dynamics combined with level-set method yields a temporally evolving turbulent extinction process and its partial quenching characteristics is compared with the results of the previous model employing the flame-hole random walk mapping. The probability to encounter reacting' state, conditioned with scalar dissipation rate, demonstrated that the conditional probability has a rather gradual transition across the crossover scalar dissipation rate in contrast to the stiff transition of resulted from the flame-hole random walk mapping and could be attributed to the finite response of the flame edge propagation.

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Simulation of a Diffusion Flame in Turbulent Mixing Layer by the Flame Hole Dynamics Model with Level-Set Method (Level-Set 방법이 적용된 Flame Hole Dynamics 모델을 통한 난류 혼합층 확산화염의 모사)

  • Kim, Jun-Hong;Chung, S.H.;Ahn, K.Y.;Kim, J.S.
    • Journal of the Korean Society of Combustion
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    • v.9 no.2
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    • pp.18-29
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    • 2004
  • Partial quenching structure of diffusion flames in a turbulent mixing layer has been investigated by the method of flame hole dynamics in oder to develope a prediction model for the phenomenon of turbulent flame lift off. The present study is specifically aimed to remedy the shortcoming of the stiff transition of the conditioned partial burning probability across the crossover condition by employing the level-set method which enables us to include the effect of finite flame edge propagation speed. In light of the level-set simulation results with two models for the edge propagation speed, the stabilizing conditions for turbulent lifted flame are suggested. The flame hole dynamics combined with the level-set method yields a temporally evolving turbulent extinction process and its partial quenching characteristics is compared with the results of the previous model employing the flame-hole random walk mapping based on three critical scalar dissipation rates. The probability to encounter reacting state, conditioned with scalar dissipation rate, demonstrated that the conditional probability has a rather gradual transition across the crossover scalar dissipation rate. Such a smooth transition is attributed to the finite response of the flame edge propagation.

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A Study of the Combustion Characteristics Using a 2-valve Sl Optically Acessible Engine with SCV (SCV를 장착한 2밸브 Sl 가시화기관의 연소특성에 관한 연구)

  • Jeong, Gu-Seop;Jeon, Chung-Hwan;Jang, Yeong-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.12
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    • pp.1692-1701
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    • 2001
  • This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve SI optically accessible engine with swirl control valve(SCV). It adapted three different types of SCV(open ratio 72.5%, 78%, 59%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt) were calculated to explain burn rate and flame speed. From acquired flame images, we inspected the flame propagation direction, flame area, and flame centroid. Flame propagation direction showed different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame images at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

In-cylinder Flame Visualization and Flame Propagation Characteristics of SI Engine by using Optimal Threshold Method (Optimal Threshold 법을 이용한 가솔린 기관의 실린더 내화염 가시화 및 화염 전파 특성에 관한 연구)

  • 김진수;전문수;윤정의
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.96-104
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    • 2000
  • It is well known that combustion stability under idle and part-load conditions directly affect fuel economy and exhaust emission. In practice, there have been a lot of studies so that a significant improvement in combustion stability has been achieved in this research field. However, applying published results to the development process of mass production engine, there are still many problems which are solved previously. In this study, initial flame behavior and flame propagation characteristic were investigated statistically in order to optimize combustion chamber shapes in the development stage of mass production S.I. engine. To the purpose, the authors applied the flame image capturing system to single cylinder optical engine. The captured flame images were effectively analyzed by using the image processing program which was developed by the authors and adopted new threshold algorithm instead of conventional histogram analysis. In addition, the cylinder pressure was also measured simultaneously to compare evaluated flame results with cylinder pressure data in terms of the combustion characteristics, combustion stability, and cycle-to-cycle combustion variability.

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