发动机换气系统三维瞬态数值模拟应用研究

通过对 K10 0二冲程汽油机倒拖工况下扫排气道 -缸内系统流场的三维瞬态数值模拟 ,发现整个扫气阶段的缸内流场是由三维回流组成的。主扫气口径向平面的切向倾斜角偏小 ,径向汇聚角偏大 ,产生了明显的短路损失 ,并在缸盖顶局部产生了反向流动形成的“死角”。为此 ,调整了主扫气口的扫气角 ,其它参数均不改变。计算结果表明 :缸内分层扫气十分清晰 ,短路损失及死角明显减少 ,反向流动被消除。但缸内回流 -环涡的流动结构基本不变

Application Research of Three-Dimensional Transient Numerical Simulation in the Scavenging System and the Cylinder for a Engine

The in cylinder flow structure of a three dimensional loop is found via three dimensional transient numerical simulation in the scavenging system and the cylinder of the Model K100 two stroke engine under cold motored condition.The slant angle of main scavenging ports in tangency direction are undersize and the converge angle in radial direction are oversize,to result in the phenomena of excessive short mix gas and scavenging dead corner of Model K100 engine.Therefore,the angle of main scavenging ports are adjusted,other parameters are not changed.The calculation results reveal the diminution of short mix gas and scavenging dead corner,and the appearance of distinctly gas delamination in cylinder,but the flow structures of loop and ring vortices change little.