燃烧室形状和位置对柴油机缸内空气运动的影响

Influence of the Shape and Offset of the Combustion Chamber on In-Cylinder Air Motion in Diesel Engines

本文利用多维数值模拟方法,进行了3个柴油机燃烧室方案下缸内三维流场的计算。系统地分析了燃烧室形状和位置对缸内流场的影响。计算表明,挤流和涡流的相互作用将使缸内涡流呈现非对称结构。一般来说,上止点时燃烧室纵剖面上的流场是一个双涡结构,但随着挤流和涡流的相对强弱变化,可能表现为不明显的双涡乃至单涡结构。反喷主要集中在燃烧室边缘处,有缩口的燃烧室的反喷更加强列。

Some in-cylinder three-demensional (3D) flow patterns for three different diesel combustion chambers have been computed by means of multidimensional modeling. The effect of the shape and offset of the bowl on the in-cylinder flow field were analysed. The computed results show that the in-cylinder flow pattern is not a symmetrical one under the interaction between swirl and squish. The flow field at TDC is nomally a double-toroidal vortex structure. Reversed squish is mainly concentrated at the edge of the combustion chamber and it would be much stronger in the case of the reentrant combustion chamber.