In this paper, the porous flow effects (tortuosity and dispersion) on the characteristics of porous combustion are numerically studied. The effects of tortuosity and dispersion are introduced in the porous diffusion coefficients to investigate the influences on the flame propagation speed and the operating range of inlet flow velocity. It is found that the ratio of thermal to mass diffusion coefficients (Le_p = α_L/D_L) due to the features of porous flow can drastically affect the flame propagation speed, which is similar to the effect of the Lewis number on the flame speed in free stream. Consequently, the results show that the operating range of inlet flow velocity (U_max–U_min) for a two-section burner can be greatly altered by the tortuosity and dispersion effects in the two porous solids. To decrease Le_p or decrease both α_L and D_L with constant Le_p in the upstream section can significantly extend the operating range by decreasing U_min; on the other hand, to increase Le_p or increase both α_L and D_L with constant Le_p can also remarkably extend the operating range by increasing U_max. Moreover, it is possible that the tortuosity effect in the upstream section (small pore) may greatly alter U_min; while the dispersion effect in the downstream section (large pore) can dominate U_max.

本文数值研究了多孔流动效应（曲折度和弥散度）对多孔燃烧特性的影响。在多孔扩散系数中引入曲折度和弥散度的影响，研究对火焰传播速度和入口流速工作范围的影响。研究发现，由于多孔流动的特性，热与质量扩散系数之比（Le _p = α _L / D _L）可以极大地影响火焰传播速度，这类似于路易斯数对火焰的影响免费流中的速度。因此，结果表明入口流速的工作范围（U _max – U _min) 对于两段式燃烧器，两种多孔固体中的曲折度和分散效应可以极大地改变。在上游段降低 Le _p或同时降低 α _L和D _L且 Le _p不变，可以通过降低U _min显着扩大工作范围；另一方面，增加 Le _p或增加 α _L和D _L并以常数 Le _p也可以通过增加U _max显着扩展操作范围。此外，上游段（小孔隙）的曲折效应可能会大大改变U_分钟；而下游部分（大孔隙）的分散效应可以支配U _max。