汽油HCCI发动机详细化学反应动力学双区模型

为考察汽油缸内直喷喷油策略对均质充量压缩着火(HCCI)燃烧的影响,在Chemkin源代码程序的基础上建立了高辛烷值汽油HCCI发动机双区燃烧数学模型。模型考虑了双区之间温度、压力以及体积的耦合,并嵌入反应传热和漏气过程的子模型,能够反映通过形成分层混合气控制HCCI燃烧的详细化学和物理过程。将双区模型和单区模型与试验结果进行对比发现,双区模型精度有了较大提高,消除了单区模型具有的压力尖峰,扩大了燃烧范围。并利用双区模型进行了HCCI发动机变工况研究,详细考察了不同分层混合气对HCCI燃烧的影响。结果表明,浓稀两区顺序放热使得缸内压力升高率降低,能够提高发动机的负荷。通过调整浓稀两区的比例,可以控制HCCI燃烧。

Two-zone chemical kinetics modeling of a gasoline HCCI engine

The effects of various direct gasoline injection strategies on homogeneous charge compression ignition (HCCI) combustion were studied using a two-zone high octane number gasoline HCCI combustion model based on the Chemkin source code. The temperatures, pressures, and species concentrations are coupled in the two zones. The model includes heat transfer and blow-by sub-models and the detailed chemical kinetics and physics of the combustion control by the stratified mixture. The two-zone model shows better agreement with experimental results than the single-zone model. The high pressure peak of the single-zone model is avoided and the combustion region is extended. Use of the two-zone model to analyze the effect of gas concentration stratification on the HCCI combustion shows that the controlled heat release reduces the pressure increase and extends the operating region so that the HCCI combustion can be controlled by adjusting the fuel ratio between the two zones.