激光诱导火花点火的现象学研究

A Phenomenology Approach on Laser-induced Spark Ignition

从激光诱导火花点火的过程出发,分析了激光诱导火花点火和激光击穿对激光器性能参数要求的不同,讨论了环境压力、温度、空燃比和气流流速等对激光最小点火能量的影响以及激光诱导火花点火技术对燃烧过程的影响。混合气浓度在当量比为1附近,激光诱导火花点火所需的最小点火能量较小,但随当量比的减小而增大,在稀燃界限附近最小点火能量迅速上升;最小点火能量随初始温度的上升而下降,随压力增大而明显降低。与火花塞点火相比,激光诱导火花点火的着火延迟短,初始燃烧速度快,循环变动小,并且稀燃界限宽。

Based on the laser-induced spark ignition process, the different requirements of laser-induced spark ignition and laser breakdown for laser performance parameters were analyzed, and the influences of ambient pressure, temperature, air-fuel ratio and air stream velocity on minimum ignition energy （MIE） and the influences of laser-induced spark ignition technology on combustion process were discussed. The needed minimum ignition energy for laser induction was less when the equivalence ratio of mixture was close to 1, increased with the decrease of equivalence ratio, rose rapidly when the equivalence ratio near the lean-burn limit, decreased with the increase of initial temperature and decreased obviously with the increase of pressure. Compared with the spark plug ignition, the ignition delay of laser-induced spark ignition was shorter, the initial combustion was more rapid, the cyclic variation was less and the lean burn limit extended.