基于模拟计算的GDI发动机燃烧室优化设计

利用AVL Fire软件,对一款高压缩比直喷汽油机的缸内流动及喷雾过程进行了数值模拟,研究了不同燃烧室设计方案对缸内流动过程的影响。结合滚流、旋流、湍动能、缸内当量比分布等8项评价指标,分析了不同方案对混合气形成的改善效果。通过分析计算结果,并引入优化率对燃烧室设计进行评估,评估结果表明,最优方案在高转速工况和低转速工况的优化率分别达到了25.3%和23.4%,发动机缸内混合气的形成过程得到了明显的改善。

Optimized Design of GDI Engine Combustion Chamber Based on Simulation and Calculation

The in-cylinder flow and spray process of a GDI engine with a high compression ratio were simulated with AVL FIRE software and the influences of different combustion chamber structures on in-cylinder flow were researched.The effects of different designs on gas mixture formation were determined based on eight kinds of evaluation parameters such as tumble, swirl,turbulent kinetic energy,in-cylinder equivalence ratio fraction and et al.Finally,the design of combustion chamber was evaluated by introducing optimization rate and analyzing the calculated results.The evaluation results show that the optimiza-tion rate of design can reach 25.3% and 23.4% in high and low speed conditions respectively according to the optimized design and hence the in-cylinder mixture formation process improves.