基于FLUENT对惰性多孔介质中湍流预混燃烧的模拟

Simulation of Premixed Turbulent Combustion in Porous Inert Media Based on FLUENT

采用了多孔介质气固间局部热平衡假定,建立了二维的多孔介质中湍流燃烧模型.通过用户自定义函数在FLUENT6.1的多孔介质模型中引入湍流和辐射的作用,对多孔介质中甲烷-空气预混燃烧的特性进行了数值模拟.得到的多孔介质中的计算流场更加合理,流速均匀且消除了多孔区近壁面速度高而中心低的不合理速度场.计算结果显示多孔介质中温度分布均匀,壁面温度和中心温度相差很小,比FLUENT软件不考虑多孔介质辐射的结果更加合理.通过计算甲烷-空气的两步反应,得到了多孔介质中速度场、温度场和浓度场的分布理论预示结果,并与试验结果进行了比较,发现二者趋势一致.利用FLUENT软件求解多孔介质中燃烧问题是有效的,该二维惰性多孔介质燃烧模型是合理的.

The local heat equilibrium between gas and solid was assumed, and a two-dimensional turbulent combustion model in porous inert media （PIM） was developed. The premixed combustion processes of methane/air in PIM were simulated based on the computational fluid dynamics （CFD） commercial software FLUENT. The turbulent effect and the radiation heat transfer due to the porous media solid matrix were considered. The porous media model in FLUENT 6,1 was modified by user-defined functions （UDFs）. The results of the velocity field became more homogeneous and logical. Otherwise, the velocity field would be obviously illogical： high velocity near the wall and low velocity in the center of the porous zone. The simulant temperature distribution is uniform and the differences between the temperature of wall and center are very few. The result is more logical than that of no solid radiant consideration. The two-stepreaction model was used and the velocity fields, temperature fields and concentration fields of the premixed combustion in PIM were predicted. The numerical results are consistent with the experimental results. The turbulent combustion model in PIM is reasonable, and using the CFD code FLUENT to solve combustion in PIM is feasible.