活塞头部形貌对汽油机爆震敏感性影响研究

基于台架试验和完整工作循环数值模拟,开展了汽油机活塞头部形貌特征对爆震的敏感性研究。以台架试验数据为基准校正了汽油机性能仿真模型,通过开展压缩比为9~16区间的外特性仿真模拟,得出压缩比为12时外特性最优。在压缩比为12的3 500r/min全负荷工况,采用化学反应动力学离子分析法,通过数值模拟分析3类基于活塞头部形貌方案的燃烧室,得出具有点火驻涡区域、气门避障区域、驻涡与避障区域之间的连通区域、后部连通区域的SABCD方案抗爆性最优,并指出活塞头部形貌特征中的连通区域对爆震敏感性具有显著影响。通过对方案SABCD的连通区域关键参数进行优化得出,当区域连通宽度和连通台阶高度均为4mm时爆震敏感性最低。研究结果表明,通过对活塞头部形貌特征的合理设计,能实现提升汽油机压缩比的同时有效抑制燃烧室对爆震的敏感性。

Effect of Piston Head Shape on Detonation Sensitivity of a Gasoline Engine

Based on the bench test and the numerical simulation over a complete working cycle, the effect of the piston head shape of a gasoline engine on detonation sensitivity was studied. By using the bench test data as the benchmark to correct the performance model of the gasoline engine, the mapping simulation for the compression of 9 to 16 was used to obtain an optimal engine map with a compression ratio of 12. The combustion characteristics of three different piston head shaped combustion chambers was analyzed by numerical simulation using the chemical reaction kinetics ion analysis method at the speed of 3500 r/min and full load with a compression ratio of 12, which shows that the SABCD scheme with rear-connected standing vortex connection channel on the piston head has the best anti-detonation properties, and the connection channel between the ignition standing vortex region and valve obstacle avoidance region has a significant impact on detonation sensitivity. By optimizing the key parameters of connection channel of the SABCD scheme, the detonation sensitivity of the piston head is the lowest when the width and depth of the connection channel are both 4 mm. Research results show that a reasonable design of the piston head shape can effectively suppress the combustion chamber''s sensitivity to detonation,while increasing the compression ratio of the gasoline engine.