点火方式对平板狭缝中预混火焰形状的影响

Effects of Ignition Methods on Premixed Flame Shape in Narrow Channels

模拟了预混乙炔-空气绝热火焰在平板狭缝中的传播,针对平面点火和火花点火对火焰形状的影响进行了重点讨论。计算结果显示,采用平面点火时,火焰在较小的狭缝通道中会形成蘑菇形状,而在较大的狭缝通道中会形成郁金香形状。而采用火花点火时,在两种通道条件下,火焰都倾向于形成蘑菇形状。根据计算结果可知,采用平面点火方式有利于郁金香状火焰的形成,而在火花点火条件下,更倾向于形成蘑菇状火焰。此结论对郁金香状火焰形成机理研究是必要的补充。

The shape of unsteady premixed flames in narrow channel with adiabatic and isothermal wall is numerically investigated in the present study. It is assumed that the flame chemistry is modeled by an one-step overall reaction which simulates the reaction of a stoichiometric acetyleneair mixture. The numerical results show that,as plane ignition is used,a mushroom-shaped flame forms finally in the light sized narrow channel, while a tulip-shaped flame appears in large sized narrow channel. As spark ignition is used,a mushroom-shaped flame is the preferred flame structure despite of sizes of the narrow channels. A specific conclusion can be drawn according to the numerical results that, as plane ignition is used, tulip-shaped flame is the preferred structure in narrow channels, while mushroom-shaped flame easily forms with spark ignition method. The drawn conclusion will be a necessary complement to the mechanisms of tulip-shaped flame formation.