二冲程发动机扫排气道-缸内系统三维瞬态数值模拟研究

摘要

Three-dimensional transient numerical simulation is studied inthe scavenging system and the cylinder of the Model K100 two-stroke motocycle engine under cold motored condition.The research results reveal that the in-cylinder flow structure established during the scavenge phase is comprised of a three-dimensional loop.The airflow similar to jet flow blends with in-cylinder gas from circumference.The airflow jostles exhaust gas out of cylinder in a way similar to encirclement.The former is similar to “perfect mixing”,the latter is similar to “perfect displacement”.Numerical simulation method is an available method to analyze complex flow field.%对倒拖工况下的K100二冲程摩托车汽油机扫排气道-缸内系统流场进行了三维瞬态数值模拟研究。通过计算发现，整个扫气阶段的缸内流场是由三维回流组成的。扫排气道-缸内系统流场是扫气气流以射流形式从周向与缸内气体混合并同时以类似环抱的形式将废气向排气口推挤，前者类似于“完全混合”，后者类似于“完全置换”。计算结果表明，数值模拟方法是分析复杂区域流场的有效方法。