声场作用下甲烷部分预混火焰NO_x生成特性实验研究

Experimental Study of NO_x Emission in Partially Premixed Flame Under Acoustic Forcing

在Rijke管产生的强迫脉动驻波声场下,以甲烷层流部分预混火焰为研究对象,比较了脉动燃烧与稳态燃烧下NO_x随当量比的变化规律,结合微细热电偶、火焰探针,讨论了火焰内部温度场和组分浓度变化,分析了脉动燃烧下NO_x降低机理。结果表明脉动燃烧下甲烷部分预混火焰的NO_x降低,其主要机理为:脉动燃烧下火焰的峰值温度低,温度分布均匀,局部高温区小;脉动使火焰内部的空气掺混量增加,强化了化学反应速率;脉动燃烧减小了反应区域,缩短了气体在高温区的停留时间,使得NO_x生成量小。

The NOx emission between pulsating combustion and non-pulsating combustion were compared on methane laminar partially premixed flame under acoustic forcing with Rijke tube. The mechanism of NOx was analyzed by micro-thermocouple, water-cooled sampling probe. The experimental results show that compared with non-pulsating combustion, pulsating combustion produced less NOx emissions. There are three reasons including： （1） peak temperature was reduced and the distribution of temperature was more uniform, （2） the oxygen of flame was increased for rapid mixing rate and the reaction rate was enhanced, （3） the reaction region of high temperature was decreased and the gas residence time was reduced for shorter flame length.