Inserting porous medium into micro-combustors is able to further enhance heat recirculation, thus favoring the extension of flame stability limits. Both experimental and numerical studies have shown that extended standing-wave combustion regimes exist in micro-combustors filled with porous medium. However, the underlying mechanism that dictates the critical flame stability limits is not well understood. As such, numerical simulations are conducted for a planar micro-combustor partially filled with porous medium in order to quantify heat transfer and to analyze its effects on the critical conditions under which flames will break the upper or lower boundaries of the porous medium. Based on the proposed definitions of the preheat zone and the heat loss zone, preheating and heat loss occurring inside the porous micro-combustor are quantified. It is shown that neither preheating nor heat loss alone is sufficient to determine the flame stability limits. Therefore, their relative importance is considered by a ratio (R_p-hl) which measures the net heat gain inside the porous zone. Making use of the correlations of R_p-hl with the flow velocity and the equivalence ratio, a flow velocity range is obtained beyond which the flame cannot be stabilized within the porous medium, regardless of the equivalence ratio used. A parametric study is subsequently carried out to examine the effects of two important parameters, they are, the thermal conductivity and the porosity of the porous medium, with the results briefly analyzed. In principal, the approach presented in this paper could be readily applied to other configurations of micro-combustors as well. By incorporating pore-scale flow, heat and mass transfer details into the numerical model, the results are expected to be more quantitatively accurate.

将多孔介质插入微型燃烧器能够进一步增强热再循环，从而有利于扩展火焰稳定性极限。实验和数值研究均表明，在充满多孔介质的微型燃烧器中存在扩展的驻波燃烧方式。但是，对临界火焰稳定性极限进行规定的基本机制尚不十分清楚。因此，对部分填充有多孔介质的平面微型燃烧器进行了数值模拟，以量化传热并分析其对临界条件的影响。在这种情况下，火焰会破坏多孔介质的上边界或下边界。基于所提出的预热区和热损失区的定义，对发生在多孔微燃烧器内部的预热和热损失进行了量化。结果表明，仅预热还是热量损失都不足以确定火焰稳定性极限。因此，它们的相对重要性通过比率（ R _p-hl）来衡量，该比率测量了多孔区域内部的净热增益。利用R _p-hl与流速和当量比的相关性，获得了流速范围，超过该流速范围，不管所使用的当量比如何，火焰都无法在多孔介质中稳定下来。随后进行了参数研究，以检查两个重要参数的影响，即导热系数和多孔介质的孔隙率，并对结果进行了简要分析。原则上，本文介绍的方法也可以很容易地应用于微型燃烧器的其他配置。通过将孔隙水流，传热和传质细节纳入数值模型，可以预期结果在定量上更加准确。