HCCI发动机多区燃烧模型的比较研究

Comparative Study on Multi-Zone Combustion Models of HCCI Engine

多区模型作为现阶段均质压燃(HCC I)发动机高效准确的数值模型得到了世界范围的广泛关注。讨论了不同子模型对多区模型预测性能的影响。以实验为基准,比较了多区模型中区间划分、缸壁传热模型、区间热量交换模型、区间质量交换模型和边界层模型对HCC I发动机燃烧和排放模拟结果的影响,全部计算均基于异辛烷的详细化学动力学机理。结果表明:在区间划分时对温度较低的区域细化可以提高排放的计算效果,而对高温区域的细化对计算结果影响不大;改进的W oschn i传热模型更准确地模拟了缸壁的传热过程;区间的质量和热量交换对计算结果影响显著,特别是质量交换模型的加入使CO排放的预测与实验值更为接近;而边界层厚度模型对整个结果影响不大。

Tthe multi-zone model has been attracting growing attention as an efficient and accurate numerical model of homogeneous charge compression ignition （HCCI） engine. In this paper, a comparative study was carried out to clarify the effect of various sub-models on predictability of the multi-zone model. The influences from zone distribution, heat transfer to wall, mass and heat exchange between zones and boundary layer thickness on HCCI engine combustion and emissions were analyzed based on the experimental data. The results indicate that making low temperature region into more zones can improve the emissions predictability. However, more zones in the hotter region have little effect on the results. The improved Woschni model significantly improves the predictability for heat transfer. It is found that mass and heat exchange between zones have great influence on the results, especially with introduction of mass exchange model, the predicted CO emission shows close value to the experimental result. The effect of boundary layer model on predictive result is slight.