双层分流燃烧室内空间利用和喷雾分布的研究

Investigation of the In-Cylinder Utilization and the Fuel Spray Distribution in the Double-Layer Diverging Combustion Chamber

应用可视化方法测试了不同喷油参数条件下3种双层分流燃烧室内的燃油喷雾扩散过程,探讨燃烧室的碰撞台、燃烧空间容积比例、燃烧空间形状等结构特征以及喷油压力和喷油正时等喷油参数对燃烧室内空间利用和燃油喷雾分布的影响.结果表明:提高喷油压力和提前喷油正时均增大了燃油喷雾的分布范围,提前喷油正时使燃油喷雾更早地进入了顶隙空间,降低了燃烧室结构对燃油喷雾分布的影响,但燃烧室的空间利用率下降;降低碰撞台位置和增大上层燃烧空间容积有利于燃烧室顶层空间的利用;剥离面可以促进下层燃烧空间内燃油喷雾的扩散;上层燃烧空间采用凸圆弧底面使燃烧室顶层区域在较早喷油正时时获得了较好的利用.

The visualization measurement was applied to measure the fuel spray spreading processes in three double-layer diverging combustion(DLDC)chambers with different injection parameters,the influence of the chamber structure features including the impinging platform,the different layer volume ratios and the layers shapes and the injection parameters such as the injection pressure and the injection timing on the in-cylinder utilization and the fuel spray distribution were discussed.The results showed that:both increasing the injection pressure and advancing the injection timing enlarged the fuel spray distribution region,advancing the injection timing made the fuel spray flow into the top clearance earlier,reduced the influence of the chamber structures on the fuel spray distribution but decreased the in-cylinder utilization rate;decreasing the impinging platform position and increasing the upper layer volume were helpful to utilize the chamber top region;the fuel stripping surface could promote the fuel spray spreading in the lower layer;the upper layer employing a convex arc bottom made the chamber top region utilized better with an earlier injection timing.