NO_x对甲烷点火延迟时间影响的数值研究

Numerical Investigation on the Effect of NO_x on Ignition Delay of Mathane

点火延迟时间是超燃冲压发动机设计中的重要参数之一。为研究氮氧化物(NO_x)对甲烷点火延迟时间的影响,在GRI-Mech 3.0机理的基础上添加R326、R327、R328 3个反应,利用CHEMKIN化学动力学软件,对CH_4/O_2/NO_x/Ar混合气体的点火过程进行数值计算,并将数值计算数据与文献[6]中的实验数据进行了对比。通过对比发现添加3个反应之后,GRI-Mech 3.0机理能够较好地模拟含NO_x时甲烷的点火过程。研究结果表明:NO_2缩短甲烷点火延迟时间的程度比N2O缩短甲烷点火延迟时间的程度大;CH_4/O_2/NO_x/Ar预混气体在富氧条件下(燃气当量比为0.5)的点火延迟时间要比贫氧条件下(燃气当量比为2.0)的点火延迟时间短。

Ignition delay time is an important parameter in the design of scramjet engine. Three reactions are added to the GRI-Mech 3.0 mechanism to investigate the effect of NO, on ignition delay of methane. The ignition process of CH4/O2/NOx/Ar mixtures is numerically calculated using the CHEMKIN chemi- cal kinetics software, and the numerical calculation data were compared with the experimental data in Ref. [ 6 ]. It is found that the GRI-Mech 3.0 mechanism could well simulate the ignition process of meth- ane with NOx when the reactions R326,R327 and R328 are added. Numerically calculated result shows that the addition of NO2, to a lesser extent of N20, leads to the reduction in the ignition delay time of CHn/O2/Ar mixtures, which is in good agreement with the experimental result of Mathieu, and the igni- tion delay time of CH4/OE/NO /Ar mixtures under the oxygen poor condition （fuel-air equivalence ratio of 0.5） is shorter than that under the fuel rich condition （fuel-air equivalence ratio of 2.0）.