二元柴油液滴碰撞过程数值模拟

Numerical simulation of binary diesel droplet collision process

为研究发动机喷雾过程中柴油液滴碰撞的物理过程,基于流体体积法(VOF)建立了两相同尺寸柴油液滴碰撞模型,利用现有的试验数据对计算模型的准确性进行了验证.同时,开展了液滴对心及偏心碰撞过程的数值模拟,得到了聚合、分离、破碎3种碰撞结果及其区域分布的We-B图,探讨了碰撞过程中所发生的能量转化机制.结果表明:对心碰撞聚合与分离的临界We数为17.3,分离与破碎的临界We数为92.0;与对心碰撞相比,偏心碰撞过程中所存在的旋转运动,导致聚合与分离的临界韦伯数随碰撞参数B的增加呈先增大后减小的趋势.

To investigate the physical process of diesel droplet collision during engine spraying,the models of two diesel droplet collision with the same size were established based on the volume of method(VOF),and the calculation model was verified using existing experiment data.The numerical simulations of droplet centering and the eccentric collision processes were carried out,and the We-B diagrams of three collision results and their regional distributions were obtained.The energy conversion mechanism occurred during the collision was discussed.The results show that the critical We number for the convergence and separation of centroid collision is 17.3,and the critical We number for the separation and fragmentation is 92.0.Compared with the centroid collision,the rotational motion during the eccentric collision causes the critical Weber number of aggregation and separation to follow the collision.The change of parameter B shows a trend of increasing with latter decreasing.