Large eddy simulation of Cambridge bluff-body coal (CCB2) flames with a flamelet progress variable model
Large eddy simulation of Cambridge bluff-body coal (CCB2) flames with a flamelet progress variable model
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DOI：
10.1016/j.proci.2020.08.020
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发表时间：
2020-10
影响因子：
3.4
通讯作者：
Jiangkuan Xing;K. Luo;Yiran Chen;O. Stein;A. Kronenburg;K. Luo;C. Hasse;Jianren Fan
中科院分区：
文献类型：
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作者：
Jiangkuan Xing;K. Luo;Yiran Chen;O. Stein;A. Kronenburg;K. Luo;C. Hasse;Jianren Fan
在本研究中，我们报告的第一个大涡模拟（LES）研究的剑桥CCB2煤火焰，在测量和模拟煤和生物质转化研讨会的目标火焰之一，与扩展的小火焰进程变量（FPV）模型。扩展的FPV模型是基于两个混合分数考虑挥发分和焦炭废气。归一化总焓用于相间传热建模。湍流化学相互作用处理与假设的概率密度函数的方法。结果表明，大涡模拟能较好地捕捉到流场和颗粒分布，但由于采用了挥发分和载气的混合物作为边界处理来代替主流和先导流中的含甲烷混合物，对OH的预测存在较大偏差.这表明，对于这种气体辅助煤火焰，引燃燃料流需要严格考虑的小火焰列表，可以通过扩展到三个混合分数模型的两个混合分数模型来解决。瞬时拉格朗日粒子历史表明，煤负荷的增加对挥发分的影响不大，但延迟了半焦的转化。
In the present study, we report the first large eddy simulation (LES) study of the Cambridge CCB2 coal flames, one of the target flames in the Workshop on Measurement and Simulation of Coal and Biomass Conversion, with an extended flamelet progress variable (FPV) model. The extended FPV model is based on two mixture fractions considering the volatiles and char off-gases. The normalized total enthalpy is used for the interphase heat transfer modelling. Turbulence-chemistry interaction is treated with an assumed probability density function approach. The results show that the present LES can generally capture the flow field and particle distribution, while there are considerable deviations in the OH prediction due to the boundary treatment of using a mixture of volatiles and carrier gas to replace the methane-containing mixtures in the primary and pilot flow. It indicates that for such gas-assisted coal flames, the pilot fuel stream needs to be rigorously considered in the flamelet tabulation that could be resolved by extending the two-mixture-fraction model into a three-mixture-fraction model. The instantaneous Lagrangian particles histories show that the increasing of coal load has a negligible effect on devolatilization, but delays the char conversion.