(2-12) A Study on Turbulent Combustion Properties of Spherically Propagating Methane Flames((SI-4)S. I. Engine Combustion 4-Flame Propagation)
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概要
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Natural gas is now considered to be one of the most promising alternative fuels for automotive engines because of the low exhaust emission characteristics and very large deposits spread around the world, much of which is not exploited. So it is important to clarify the nature of this energy source. The purpose of this paper is to examine the turbulent combustion properties of methane, which is the main component of natural gas, considering the application to spark-ignited engines. The below left figure shows the experimental result on turbulent burning velocities, S_T, as a function of turbulence intensity, u', where both values are non-dimensionalized by the corresponding laminar burning velocities, S^o_u, using a constant-volume combustion bomb. From the figure, it is found that for methane mixtures the leaner mixtures become, the larger the turbulent burning velocities even at the same turbulent intensity. We have inferred that this effect is caused by the change in local burning velocity due to the flame stretch to which each local flamelet in a turbulent flame is subjected. In this case, the local burning velocity of each flamelet changes from the unstretched laminar burning velocity with increasing stretch near-linearly. According to the asymptotic analysis, general relation can be expressed as the below equation. [numerical formula] Where S_u is stretched laminar burning velocity, Ka is non-dimensional flame stretch, characterized by Karlovitz number. So it is found that Ma, which is referred to as Markstein number, represents the sensitivity of local burning velocity to flame stretch. At the same value of Ka, mixture with the smaller value of Ma has the larger value of S_u/S^o_u. So in turn we have investigated the correlation between Markstein numbers and turbulent burning velocities. The below right figure shows the variations of Markstein numbers with equivalence ratio, which were obtained in this study and cited from other studies. From the figure, for methane mixtures Ma is found to decrease with decreasing equivalence ratio, indicating that the stretched burning velocity is estimated to relatively increase on fuel leaner region. These trends quantitatively agree with those of turbulent burning velocities, as seen in left figure. From the above discussion, it can be concluded that methane intrinsically favors lean burn combustion. And this can be explained by the difference in sensitivity to flame stretch.
- 一般社団法人日本機械学会の論文
- 2001-07-01
著者
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Kido Hiroyuki
Kyushu University Dept. Of Mechanical Science And Engineering
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Tanoue Kimitoshi
Department Of Mechanical Engineering Oita University
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Tanoue Kimitoshi
Oita University Dept. Of Mechanical Engineering Faculty Of Engineering
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SHIMADA Fumio
Oita University, Dept. of Mechanical Engineering, Faculty of Engineering
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AI Takeshi
Oita University, Dept. of Mechanical Engineering, Faculty of Engineering
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Ai Takeshi
Oita University Dept. Of Mechanical Engineering Faculty Of Engineering
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Shimada Fumio
Oita University Dept. Of Mechanical Engineering Faculty Of Engineering
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Tanoue Kimitoshi
Graduate School Kyushu University
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KIDO Hiroyuki
Kyushu Polytechnic College
関連論文
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- Experimental study of the turbulent combustion mechanism of non-stoichiometric mixtures
- Study of Burning Velocities of Dimethyl Ether-Air Flames(S.I. Engines, Flame Propagation)
- TED-AJ03-144 EFFECTS OF FLAME STRETCH ON LAMINAR METHANE FLAMES WITH HYDROGEN ADDITION
- Effects of Flame Stretch on Turbulent Combustion Properties of Spherically Propagating Premixed Flames
- The Effects of Flame Stretch on Outwardly Propagating Flames
- (2-12) A Study on Turbulent Combustion Properties of Spherically Propagating Methane Flames((SI-4)S. I. Engine Combustion 4-Flame Propagation)
- B304 A STUDY ON TURBULENT BURNING VELOCITY OF METHANE MIXTURES WITH HYDROGEN ADDITION(Turbulent flame-1)
- Studies of Combustion Properties of Dimethyl Ether Flames
- Effect of Stretch on Local Burning Velocity of Premixed Turbulent Flames
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