喷射时刻对焦炉气直喷发动机燃烧特性影响

摘要

为加强焦炉气的利用,减少资源浪费,利用AVL-FIRE软件对焦炉气缸内直喷型发动机进行建模,模拟不同喷射时刻对于该类型发动机燃烧过程及排放的影响,以确定焦炉气的最佳喷射时刻.结果表明:在相同燃气喷射量与喷射持续期下,最佳喷射时刻出现在进气门关闭后开始喷射且点火前结束喷射期间.最佳喷射时刻使得缸内混合气形成均匀,燃气浓度与湍流强度分布有利于加快火焰传播速度,实现稳定燃烧,提高缸内压力,降低NOx排放,过早与过晚喷射均会降低发动机动力性能.%In order to improve the utilization of COG and reduce resource waste, the simulation model of a direct injection COG engine was established based on AVL-FIRE. Effects of injection timings on combustion and emission characteristics were investigated by simulation. Resultsshowed that the optimum fuel injection timing existed under the same gas injection volume and injection duration,where both concentration of mixture gas and distribution of turbulence intensity were helpful to accelerate the flame propagation speed,form stable combustion,increase the pressure in cylinder and reduce the emissions of NOx.Early and late injection would reduce the engine performance.