本生灯预混火焰淬熄距离实验分析

淬熄距离是表征壁面淬熄效应的一项重要参数.通过直接拍摄火焰位置图片,得到甲烷本生灯预混火焰淬熄距离随来流预混气速度与当量比的变化关系.实验结果表明,本生灯火焰淬熄距离随来流速度的变化规律在不同当量比范围内是不同的.而在同一速度下,随来流当量比增大,淬熄距离贫油时减小,富油时先增大再减小,最后在某一当量比时淬熄距离保持一个定值.这一变化关系是由来流预混气对壁面的冷却作用和火焰面对壁面的加热作用共同影响所造成的,尤其是富油预混火焰的双层结构会极大地影响淬熄效应.

Experimental analysis of wall quenching distance of a premixed Bunsen flame

Quenching distance is a major parameter to characterize the flame wall quenching effect. The quenching distance of a methane-air premixed Bunsen flame was measured using direct photography of the flame position. The result indicates that the quenching distance changes differently with the incoming flow velocity under different equivalence ratio ranges. While the velocity is fixed, the quenching distance decreases with the increasing equivalence ratio for the lean flame. For the rich flame the quenching distance first increases and then decreases, and keeps a constant after a certain equivalence ratio. This correlation is induced by the competition between the cooling of the wall by incoming flow and the heating of the wall by flame. The double-flame structure of a premixed rich flame especially influences the wall quenching effect very remarkably.