A good mixing of reactants is important for non-premixed combustion in miniature combustors. In this paper, mixings of methane and oxygen in Y-shaped mesoscale combustors with and without porous media were compared numerically. The results show that when there is no porous media in the horizontal channel, the mixing becomes worse with the decrease of the included angle between two inlets, or with the increase of inlet velocity. The reason is that for the case without porous media, the dominant mixing mechanism is molecular diffusion under concentration gradients. In contrast, for the case with porous media, due to the mass dispersion effect which becomes more significant with the decrease of channel width, satisfactory mixing can always be attained in the Y-shaped mesoscale combustor. Moreover, fairly good mixing can still be achieved in the horizontal channel of shorter length. All these demonstrate that the porous media greatly promotes the methane/oxygen mixing in the Y-shaped mesoscale combustor, which is beneficial for flame stabilization. Meanwhile, the combustor dimension can be further scaled down because good mixing is possible in the channel with even smaller included angle and shorter length. This is very important for the application of miniature power generation system.

反应物的良好混合对于微型燃烧器中的非预混合燃烧很重要。在本文中，比较了在有和没有多孔介质的Y型中尺度燃烧室中甲烷和氧气的混合情况。结果表明，当水平通道中没有多孔介质时，随着两个入口之间夹角的减小或入口速度的增加，混合变得更糟。原因是在没有多孔介质的情况下，主要的混合机制是浓度梯度下的分子扩散。相反，对于具有多孔介质的情况，由于质量分散效果随着通道宽度的减小而变得更加显着，因此在Y形中尺度燃烧室中始终可以实现令人满意的混合。此外，在较短长度的水平通道中仍然可以实现相当好的混合。所有这些表明，多孔介质极大地促进了Y型中尺度燃烧室中甲烷/氧气的混合，这有利于火焰稳定。同时，燃烧器的尺寸可以进一步缩小，这是因为在具有较小夹角和较短长度的通道中可以进行良好的混合。这对于微型发电系统的应用非常重要。