关键词: 等离子体；物理模型；数值模拟；约化场强；粒子演化；点火延迟

Abstract: The density equation，energy transfer equation as well as Boltzmann equation were coupled aimed at analyzing particles concentration of pulsed discharge in order to study the effect in reducing ignition delay acted by plasma during the discharge. The excited molecular and active radical calculated were added as initial components in CHEMKIN model. The influence of methane ignition delay at the discharge was calculated. The cross section of elastic，excitation and ionization is 2~5 orders of magnitude larger than that of attachment. The excitation process leads to more than 80% energy loss of the mixed gas. With the increase of particle energy，each cross section of process is not monotonous. There were maximum values for each process. The ionization effect of methane is gradually enhanced with the increasing of the reduced electric field. Energy loss of attachment and elastic is smaller for the mixed gas compared with the excitation and ionization. Therefore it can be ignored. It can produce a large number of different kinds of active particles and radicals during the discharge process，and the changing rule of different active particles over time is different. The concentration of vibration excitation nitrogen molecules keeps 1015/cm3 orders of magnitude with the discharge. The concentration of ionization excitation nitrogen molecules produces a peak in 10-8s～10-7s with the discharge. The active particles produced by single pulsed discharge could shorten the ignition delay by 10% at least in most of the ignition temperature. Pulsed discharge can enhance the ignition of methane-air mixed gas dramatically.

Key words: Plasma；Physical model；Numerical simulation；Reduced electric field；Particle evolution；Ignition delay