高压缩比甲醇发动机中爆轰现象研究

摘要

Excessive increase of methanol engines compression ratio will lead to severe knock,which will dam-age the piston.In order to reveal such a severe knock phenomenon,our research conducted several numerical simulations and then analyzed the chemical process of end gas,which revealed the mechanism that compression waves cause auto-ignition while auto-ignition also affect compression wave.The results indicate that detonation waves are formed in two ways.One way is the transition of deflagration to detonation which occurs on the normal flame front,and the other way is the direct initiation of detonation which occurs on the auto-ignition point.The compression waves formed earlier continue oscillating in the cylinder,promoting the low-temperature reaction of end gas,which provides enough radicals for the formation of detonation.%甲醇发动机在压缩比过度提高后会出现烈性爆震,甚至造成对活塞的破坏.为了揭示这种烈性爆震现象,本研究进行了数值模拟计算,分析了末端混合气的化学反应过程,揭示了压力波导致自燃、自燃又反过来影响压力波的机理.研究结果表明,有两种方式导致了爆轰波的形成,第一种是爆燃转爆轰,该过程发生在正常火焰面上;第二种是直接起爆,该过程发生在自燃点上.早期形成的压力波在缸内振荡,促进了末端混合气的低温反应,为爆轰的形成积累了充足的自由基.