Experimental and numerical study of soot formation in counterflow diffusion flames of gasoline surrogate components
Experimental and numerical study of soot formation in counterflow diffusion flames of gasoline surrogate components
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DOI：
10.1016/j.combustflame.2019.08.013
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
S. Kruse;Achim Wick;J. Beeckmann;H. Pitsch;P. Medwell
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文献类型：
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作者：
S. Kruse;Achim Wick;J. Beeckmann;H. Pitsch;P. Medwell
对乙烯和正庚烷、异辛烷和甲苯三种典型汽油替代组分在层流对流扩散火焰中的碳烟形成进行了实验和数值研究。采用激光诱导白炽和消光技术来确定在燃烧器的良好控制区域内的烟灰体积分数。实验进行了广泛的应变速率和化学计量的混合分数。从实验数据，碳烟的形成应变速率和化学计量混合分数的敏感性，推导出每种燃料。燃料显示出明显不同的敏感性。对于异辛烷和正庚烷，与乙烯和甲苯相比，观察到碳烟产生对应变速率的更高敏感性。此外，碳烟形成对应变速率的敏感性随着化学计量混合物分数的增加而增加。一维模拟实验研究的火焰进行了使用两种不同的详细的化学动力学机制，详细的化学烟尘模型，和混合动力矩法以及离散截面法来描述烟尘动力学。该模型是能够预测的碳烟体积分数的乙烯火焰具有显着的准确性，而汽油替代组件，整体碳烟体积分数被overpredicted为所有测试模型。在异辛烷火焰中，烟灰成核和PAH冷凝速率特别增强。反应路径分析表明，在乙烯火焰中，苯的形成主要来自乙炔，而对于异辛烷，大量的异丁烯基形成丙炔，炔丙基，然后苯。
Soot formation is experimentally and numerically investigated in laminar counterflow diffusion flames burning ethylene and three typical gasoline surrogate components; n-heptane, iso-octane, and toluene. Laser-induced incandescence and a light extinction technique are employed to determine the soot volume fraction within the well-controlled region of the burner. The experiments are performed across a wide range of strain rates and stoichiometric mixture fractions. From the experimental data, sensitivities of soot formation on strain rate and stoichiometric mixture fraction are derived for each fuel. The fuels show significantly different sensitivities. For iso-octane and n-heptane, a higher sensitivity of soot production on the strain rate is observed as compared to ethylene and toluene. Moreover, the sensitivities of soot formation on the strain rate increase with increasing stoichiometric mixture fraction. One-dimensional simulations of the flames investigated experimentally were performed using two different detailed chemical kinetic mechanisms, detailed chemical soot models, and the hybrid method of moments as well as a discrete sectional method to describe soot dynamics. The models are capable of predicting the soot volume fraction of the ethylene flames with remarkable accuracy, whereas for the gasoline surrogate components, the overall soot volume fractions are overpredicted for all tested models. In iso-octane flames, soot nucleation and PAH condensation rates are particularly enhanced. A reaction pathway analysis shows that in ethylene flames, the formation of benzene mostly originates from acetylene, while for iso-octane, large amounts of iso-butenyl form propyne, propargyl, and then benzene.