Flame structure and radiation characteristics of CO/H2/CO2/air turbulent premixed flames at high pressure
Flame structure and radiation characteristics of CO/H2/CO2/air turbulent premixed flames at high pressure
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DOI：
10.1016/j.proci.2010.05.068
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发表时间：
2011-01-01
影响因子：
3.4
通讯作者：
Kadowaki, Satoshi
中科院分区：
文献类型：
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作者：
Ichikawa, Yasuhisa;Otawara, Yuki;Kadowaki, Satoshi
以CO/H-2/CO2/空气为模型，在1.0MPa的高压环境下对煤气化合成气湍流预混火焰进行了实验研究。采用与CO/H2/CO2/空气混合物相同的层流燃烧速度和绝热火焰温度的CH 4/空气火焰，用OH-PLIF分析了火焰结构、湍流燃烧速度和火焰辐射特性。结果表明，在CO/H-2/CO2/空气火焰的情况下，可以看到非常细的尖点，这些小尖点即使对于低u '/S-L也是在大尺度褶皱火焰前缘上产生的。高压下CO/H2-/CO2/空气火焰的火焰面密度高于CH 4/空气火焰，湍流火焰区的平均体积小于CH 4/空气火焰。对于CO/H-2/CO2/空气火焰，在该实验中没有观察到S-T/S-L随u ′/S-L的弯曲，而对于CH 4/空气火焰，清楚地看到这种弯曲。弯曲特性的差异可以解释基于分形内截止所代表的火焰褶皱的最小尺度与特征火焰不稳定尺度之间的尺度关系。CO/H2-/CO2/空气火焰在0.5 MPa下的火焰辐射光谱在可见光波长范围内显示出连续的发射，而对于当量比为1的CH 4/空气火焰，在IR范围内显示出非常强烈的H2O发射。当比较绝热火焰温度相同的CO/H-2/CO2/空气火焰和CH 4/空气火焰时，观察到前者的总辐射强度较强。CO/H-2/CO2/空气火焰的强烈辐射被认为是产生非常细的火焰尖的机制之一，因为对于较小的刘易斯数，增强了细胞不稳定性。(C)2010燃烧研究所。爱思唯尔公司出版All rights reserved.
Experimental study on turbulent premixed flames for a CO/H-2/CO2/air mixture as a model of coal gasification syngas in a high pressure environment was performed up to 1.0 MPa. CH4/air flames with laminar burning velocity and adiabatic flame temperature identical to those of CO/H-2/CO2/air mixture were also employed, and then the flame structure and turbulent burning velocity analyzed using OH-PLIF as well as flame radiation characteristics were compared. Results showed that in the case of the CO/H-2/CO2/air flame, very fine cusps were seen, these small cusps being generated on a large scale wrinkled flame front even for low u'/S-L. Flame surface density of the CO/H-2/CO2/air flame was higher than that of the CH4/air flame, and the mean volume of the turbulent flame region of CO/H-2/CO2/air flame was smaller than that of the CH4/air flames at high pressure. Bending of S-T/S-L with u'/S-L for the CO/H-2/CO2/air flame was not observed in this experiment, while such bending was clearly seen for the CH4/air flame. The difference in the bending characteristics can be explained based on the scale relation between the smallest scale of flame wrinkles represented by the fractal inner cutoff and characteristic flame instability scale. The spectrum of flame radiation for the CO/H-2/CO2/air flame at 0.5 MPa showed continuous emission in the visible range of the wavelength, while that for CH4/air flames for the equivalence ratio of unity showed very intense H2O emission in the IR range. When the flames with identical adiabatic flame temperature for the CO/H-2/CO2/air flame and the CH4/air flame were compared, the total radiation intensity of the former mixture was observed to be strong. The intense emission from the CO/H-2/CO2/air flame is thought to be one of the mechanisms which generate very fine flame cusps as enhanced cellar instability for smaller Lewis number. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.