Abstract: In the present paper, the effect of solid material on the blow-off limit of a micro-combustor was numerically investigated. For the three solid materials selected, i.e., quartz, stainless steel, and SiC, the corresponding blow-off limits obtained for the three combustors are 36, 25 and 21 m·s^-1. The underlying mechanisms are analyzed in terms of the interactions between heat transfer, flow field and flame stabilization. It is revealed that for small thermal conductivity (i.e., quartz), less heat is conducted to upstream walls, the fresh mixture is not sufficiently preheated, and the gas volume does not expand so significantly, leading to a larger "low velocity zone" and thus a higher blow-off limit. For the other two materials with higher thermal conductivities (i.e., stainless steel and SiC), higher thermal emissivity (i.e., SiC) results in higher "total heat loss ratio" and lower blow-off limit. It can be concluded that the solid material with a relatively low thermal conductivity and emissivity is beneficial to obtain higher blow-off limit for the micro bluff body combustor.

Key words: microscale, blow-off limit, solid material, flow field, heat transfer, numerical simulation

摘要： 通过数值模拟研究了固体材料（石英、不锈钢和SiC）对微型钝体燃烧器内氢气/空气预混火焰的吹熄极限的影响。结果表明：计量比为0.5时，3个燃烧器对应的吹熄极限分别为36、25和21 m·s^-1。理论分析揭示了微型钝体燃烧器中火焰稳定性与流动和传热之间的相互作用非常密切。当热导率较小时，通过壁面向上游传导的热量较少，壁面对未燃预混气的预热效果较差，燃烧后的气体膨胀相对较弱，从而钝体后的低速区面积较大，稳燃效果较好。对于不锈钢和SiC燃烧器，由于SiC的发射率更大，通过壁面的散热损失较大，从而使得其吹熄极限较小。为获得良好稳燃性能的微型钝体燃烧器选择合适的材料提供了指导。

关键词: 微尺度, 吹熄极限, 固体材料, 流场, 传热, 数值模拟