当量比对CNG发动机动力及排放性能的影响

为了研究缸内直喷稀燃CNG发动机在不同当量比条件下的动力及NO排放性能,利用AVL Fire建立了发动机仿真模型,通过样机试验确定了仿真初始参数和边界条件;通过软件仿真发现了气缸内微观三维物理场与缸内压力、燃烧放热率和NO生成量间的内在联系,总结出了CNG发动机中导致NO快速生成的因素,并给出了能够在保证发动机动力性提升的同时降低NO生成量的最优当量比范围。

Effect of Equivalence Ratio on CNG Engine Power and Emission

In order to study the power and NO emission performance of in-cylinder direct lean-burn CNG engine under differ-ent equivalent ratios,the engine simulation model was established by using AVL Fire.The initial parameters and boundary con-ditions of simulation were determined by the prototype experiment.The internal relationships between in-cylinder microscopic three-dimensional physical field and combustion pressure and between combustion heat release rate and NO production were found through the simulation.Then the factors of NO rapid generation in CNG engine were summarized and the optimal equiva-lent ratio range that could improve the engine power and reduce the NO emission was put forward.