快速压缩装置角涡运动特性

The numerical study of corner vortex characteristics in a rapid compression machine for gas engines

针对内燃机快速压缩装置(RCM)内部的典型涡旋流动,采用CFD方法对不同边界条件和变比例几何模型下的内燃机汽缸模型RCM内涡旋的形成与分布特征进行了数值模拟分析.结果表明:RCM的汽缸与活塞形成的角区附近存在一对反向旋转的涡旋,通常情况下,角区涡将充满整个活塞壁.模型的几何尺寸比例对RCM内部的涡流动有显著影响:随着几何尺寸的变化,在靠近活塞壁面附近会出现一对稳定的反向涡,也会出现一个主涡和多个辅涡共存的复杂流道状态.

To make the classic vortex motion clear in the rapid compression machine （RCM）, the computational fluid dynamics（CFD） method was used to simulate the flow field in a cylindrical model of a gas engine with various boundary conditions and geometry ratios. The characteristics of the vortex motion including shape, position, and scale were analyzed. The results show that a couple of reversed vortices exist at the corner between the cylinder wall and piston wall which customarily seized on the whole piston wall. The geometry ratio had a great significance on the vortex motion; with the geometry ratio increasing or decreasing, the flow field near the piston wall was filled with a couple of reversed vortices or a muhi-vortex of a central vortex surrounded by several minor vortexes.