• Title/Summary/Keyword: pre-Mixture Flame

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A Study on the Control of Flame Shapes in Laminar Pre-Mixed Flames (층류 예혼합화염의 화염면 형상 제어에 관한 연구)

  • Lee, Won-Nam;Seo, Dong-Kyu
    • 한국연소학회:학술대회논문집
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    • 2003.05a
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    • pp.103-108
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    • 2003
  • The control of flame shapes in a laminar pre-mixed flame has been experimentally investigated for propane/air pre-mixed laminar flames. Flames of different size and shapes are observed with heated wires or by controlling the equivalence ratio and flow rate of a mixture. The characteristics of the partitioning of a flame or the merge of flames are analyzed and explained by considering the balance between laminar flame speed and upstream mixture velocity. A combustor might be sized down while maintaining its heat production rate the same by partitioning a flame established in it. When the equivalence ratio of mixture is decreased, individual flames are merged together and the upstream mixture velocity can be practically decreased on a nozzle having opening ratio less than unity. As a result, the flame shape is to he adjusted until the newly established balanced condition is satisfied, and then. the stable combustion can be achieved again.

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Flame Visualization and Flame Characteristics of Spark Plug with Pre-ignition Chamber (예연소실 점화플러그의 화염가시화와 화염전파특성)

  • Jie, Myoung Seok;Johng, In Tae
    • Journal of the Korean Society of Visualization
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    • v.14 no.3
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    • pp.51-58
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    • 2016
  • New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

Combustion in Methane-Air Pre-Mixture with Water Vapor(1) - Progress of Flame Propagation (물 혼합에 의한 메탄-공기 예혼합기의 연소(1) - 화염전파과정)

  • Kwon, Soon-Ik
    • Journal of the Korean Society of Industry Convergence
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    • v.11 no.1
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    • pp.5-10
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    • 2008
  • A flame speed of methane mixture of water vapor and air have been measured to study the process of flame propagation using schlieren photographs. The quantity of water vapor contained were changed 5% and 10% of total mixture, and equivalence ratio of mixture between 0.8 and 1.2 were tested under the ambient temperature 323K and 373K. The results showed that the burning velocity was decreased by increasing the water vapor contents due to the interruption of flame development. And, the reduction rate of burning velocity was smaller by increasing the water contents under the same ambient temperature. The effects of ambient temperature on burning velocity was decreased by increasing the water vapor contents.

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Numerical Analysis on the Triple Flame Structure with Different Kinds of Fuel (3중화염의 구조에 미치는 연료종류에 관한 수치해석)

  • 최낙정
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.1
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    • pp.88-95
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    • 1999
  • This study investigates the effects of different kind fuels on the flame structure by using the numerical simulation in triple flame made by a co-flowing fuels-air stream based on the elementary chemical reaction mechanism. Methane and Hydrogen were used as fuel for this study. In order to interpret the result of the study on numerical simulation Skeletal chemistry is employe as the elementary chemical reaction mechanism for methane Gutheil's as an offset ele-mentary chemical reaction mechanism for hydrogen. The result of this study is as follows. In com-parison between the apparent burning velocity change of triple flame and the one-dimensional pre-mixed flame hydrogen fuel flame is higher than methane fuel flame. The flame thrusts out for-ward in the down stream of the boundary between air-fuel mixture and air stream and a part of the flow is bent and forks out in this protruding flame so that a triple flame is originated.

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Prediction of Laminar Burning Velocity and Flame Thickness in Methane-Air Pre-Mixture (메탄-공기 예혼합기에서의 층류 화염속도 및 화염두께 예측)

  • Kwon, Soon-Ik;Bowen, Philip J.
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.9
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    • pp.1201-1208
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    • 2003
  • The thickness of flame and preheat zone from burning velocity which was computed by using Premix code of Chemkin program for methane-air mixture. Also the thickness was evaluated from temperature profile which is also obtained from Premix code for the equivalence ratio of 0.5 to 1.6. The computations were carried out for the laminar flame thickness and burning velocity under the unburned gas temperature 0.5bat-30bar and temperature of 300K-700K at ${\Phi}=l.0$. Comparison of the results showed no difference between these two methods. The flame thickness was decreased by increasing the pressure and temperature, but, the affect of pressure is more significant than the effect of temperature on the flame thickness. The thickness of preheat zone was about 66.5% of the flame thickness, and flame thickness and burning velocity were also predicted by using empirical equation.

An Experimental Study on the Flame Localization Characteristics and Pulsating Instability in a Radial Multi-channel (반경방향 다중 채널 내 예혼합 화염의 안정화 특성과 맥동 불안정성에 관한 실험적 연구)

  • Lee, Dae Keun;Ko, Chang-Bog
    • 한국연소학회:학술대회논문집
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    • 2013.06a
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    • pp.41-43
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    • 2013
  • In order to simulate and visually observe combustion phenomena in cylindrical radial-flow porous inert media, a radial multi-channel burner, made of transparent quartz plates, was fabricated. Flame stabilization characteristics and its pulsating instability in the burner were experimentally investigated with respect to various mixture flow rates and equivalence ratio. As a result, five different flame behaviors, such as stable flame, pulsating instability, sudden extinction, blowout and unstable extinction, were observed. Mean radial position of circularly arranged multi-flame and its averaged burning velocity were measured and then compared to the freely propagating flame. The multi-flame pulsation frequency is about several tens of Hz and it is supposed to be generated by the heat diffusion enhancement to cold pre-mixture by the intensive gas-solid interaction.

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A Study on the Combustion Characteristics of Spark Plug with Pre-ignition Chamber (예연소실을 갖는 점화플러그의 연소 특성에 관한 연구)

  • Jie, Myoung-Seok;Kim, Jin-Hyuck;Yoo, Seong-Yeon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.8
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    • pp.718-723
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    • 2007
  • The new concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber in the lower end of spark plug and flame hole, in which fresh mixture gas can be introduced without any fuel supply system. This spark plug was tested with a commercial SI engine. Fuel consumption rate, emission gas and MBT timing were measured in the engine dynamometer for various flame hole numbers, hole positions, hole sizes of the pre-ignition chamber of the spark plug. And average flame propagation speed was measured by using the head gasket ionization probe in single cylinder engine. The new concept spark plug induces fast bum in combustion compared with the conventional spark plug, and MBT(Minimum advance for Best Torque) timing was retarded about $3{\sim}5^{\circ}$ crank angle. The flame hole number, hole direction and volume of pre-ignition chamber were found to influence the combustion characteristics.

Combustion Characteristics of Methane/Oxygen Gas in Pre-mixed Swirl Flame (메탄/순산소 예혼합 화염의 선회 특성)

  • Choi, Won-Seok;Kim, Han-Seok;Cho, Joo-Hyeong;Kim, Yong-Mo;Ahn, Kook-Young;Woo, Ta-Kwan
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.1979-1983
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    • 2008
  • The effects of carbon dioxide addition to oxygen have been investigated with swirl-stabilized premixed methane flame in a laboratory-scale pre-mixed combustor. The methane fuel and oxydant mixture gas ($CO_2$ and $O_2$) were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame characteristics were examined for different amount of carbon dioxide addition to the methane fuel and different swirl strengths. The effects of carbon dioxide addition and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using chemiluminescence techniques to provide information about flow field. The results show that the flame area increases at upstream of reaction zone because of increase in recirculation flow for increase in swirl intensity. The flame area is also increased at the downstream zone by recirculation flow because of increase in swirl intensity which results in higher centrifugal force. The OH and CH radical intensity of reaction zone decrease with carbon dioxide addition because the carbon dioxide plays a role of dilution gas in the reaction zone.

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Prediction of Laminar Flame Thickness of Ethanol-Air Pre-Mixture (에탄올-공기 예혼합기의 층류 화염두께 예측)

  • Kwon, Soon-Ik;Kim, Sang-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.11
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    • pp.1417-1423
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    • 2004
  • The thickness of laminar flame and preheat zone was computed from equation with burning velocity and the temperature profile, which is obtained by using premix code of Chemkin program for ethanol-air mixture. The computations were carried out under the unburned gas pressure 0.5bar-30bar and temperature of 300k-700K at 1.0. A difference flame thickness showed between temperature profile and equation with burning velocity. The ratio of flame thickness derived from the equation was about 45∼65% of the temperature profile, and the thickness of preheat zone was about 67.1% of the flame thickness. The flame thickness was decreased by increasing the pressure and temperature, but the effect of pressure is more significant than the effect of temperature on the flame thickness. The flame thickness was predicted by using the following equation. X(mm) = $X_{st}$ (T/300)$^{-0}$.65/(P)$^{-0}$.68/ (0.5bar$\leq$P$\leq$30bar, 300K$\leq$T$\leq$700K)K)

Combustion Characteristics of Hydrogen/Methane gas in Pre-mixed Swirl Flame (메탄/수소 혼합 가스의 예혼합 선회 연소특성)

  • Kim, Han-Seok;Lee, Young-Duk;Choi, Won-Seok;Ahn, Kook-Young
    • Journal of Hydrogen and New Energy
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    • v.19 no.4
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    • pp.276-282
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    • 2008
  • The effects of hydrogen enrichment to methane have been investigated with swirl-stabilized premixed hydrogen-enriched methane flame in a laboratory-scale pre-mixed combustor. 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 characteristics were examined for different amount of hydrogen addition to the methane fuel and different swirl strengths. The hydrogen addition effects and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using micro-thermocouple, particle image velocity meter (PIV) and chemiluminescence techniques to provide information about flow field. The results show that the flame area increases at upstream of reaction zone because of increase in ignition energy from recirculation flow for increase in swirl intensity. The flame area is also increased at the downstream zone by recirculation flow because of increase in swirl intensity which results in higher centrifugal force. The higher combustibility of hydrogen makes reaction faster, raises the temperature of reaction zone and expands the reaction zone, consequently recirculation flow to reaction zone is reduced. The temperature of reaction zone increases with hydrogen addition even though the adiabatic flame temperature of the mixture gas decreases with increase in the amount of hydrogen addition in this experiment condition because the higher combustibility of hydrogen reduces the cooler recirculation flow to the reaction zone.