非平衡等离子体对降低点火延迟的数值研究  

Numerical Simulation of Nonequibrium Plasma on Ignition Delay

作　　者：刘肖[1] 汪春梅[1] 李晶晶[1] 姚登举[1] 彭杨茗 

机构地区：[1]合肥工业大学机械与汽车工程学院,安徽合肥230009

出　　处：《内燃机与动力装置》2015年第3期66-70,共5页Internal Combustion Engine & Powerplant

基　　金：国家自然科学基金资助项目(11147027)

摘　　要：针对航空发动机燃气停留时间短难以充分燃烧以及稀薄燃烧中点火能过高和火焰传播速度慢的缺陷,引入高压纳秒脉冲放电作为甲烷-空气混合气的点火源,利用放电产生的非平衡等离子体改善点火和燃烧性能。通过对放电过程的模拟计算,分析产生的粒子种类和密度,从电子能量分布的角度,分析粒子分布变化的机理。再结合CHEMKIN多区模型,研究放电产生的粒子在着火过程中对点火延迟产生的影响。结果表明,约化场强处于200~400 Td区间时产生单个自由基的能量消耗最低,每个自由基仅消耗8 e V。而随着约化场强增加,O、OH等自由基的粒子密度有不同幅度的增加。在着火过程中加入自由基的摩尔分数越大,点火延迟时间越短。将约化场强为400 Td时产生的自由基摩尔分数加入多区模型,稀燃时的点火延迟时间与化学当量比条件下的相比降低了24.4%。In this work the nanosecond pulsed power was used to ignite the methane - air mix- ture for insufficient combustion in aero -engines and excessive high ignition energy and slow flame propagation velocity in lean mixture. The plasma produced in discharge was used to improve the ig- nition and combustion property. The variety and density of radical was analyzed by simulation of dis- charge, and the distribution of radical was analyzed with the perspective of electron energy distribu- tion. Combining with the multi - zone model CHEMKIN, the influence of radical for ignition delay was investigated. The results show that the energy consumption for every radical was lowest （8ev/ radical） while the reduced electric field was from 200 to 400Td. As the reduced electric field was enhanced, the density of O and OH was growing. And the ignition delay was shortened with the con- centration of radical increase. Ignition delay in lean mixture was 24.4% shorter than the stoichio- metric ratio when the reduced electric field was 400Td.

关 键 词：非平衡等离子体 点火延迟 电子能量分布 约化场强 

分 类 号：TK402[动力工程及工程热物理—动力机械及工程]