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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2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2区的比例,可以控制HCCI燃烧。
In order to investigate the influence of direct injection strategy of gasoline cylinder on homogeneous charge compression ignition (HCCI) combustion, a two-zone combustion mathematical model of high-octane gasoline HCCI engine was established based on Chemkin source code. The model takes into account the coupling of temperature, pressure and volume between two zones and embeds a submodel of reaction heat transfer and blowdown processes that reflects the detailed chemical and physical processes that control HCCI combustion by forming a stratified mixture. Comparing the two-zone model and the single-zone model with the experimental results, it is found that the precision of the two-zone model has been greatly improved, the pressure spikes in the single-zone model have been eliminated and the combustion range has been enlarged. The two-zone model has also been used to make the HCCI engine variable Working conditions, the impact of different stratified mixture on HCCI combustion was examined in detail. The results show that the exothermic sequence of concentrated dilute zone 2 causes the pressure increase rate in the cylinder to decrease, which can increase the engine load. HCCI combustion can be controlled by adjusting the ratio of concentrated dilute zone 2.