内燃机气缸内滚流比的预测与分析

Prediction and Analysis of Tumble Ratio in Cylinder

常用的滚流公式计算结果大于气缸内流场的LDA或热线风速仪实测结果,通过分析滚流形成的物理过程,提出临界曲轴转角概念,指出在临界曲轴转角内滚流无法形成,上一循环残余废气的滚流角动量是0,充气效率也对滚流角动量有影响,包含这些因素的滚流比数学表达式更合理。

The calculation value coming from traditional tumble formula is bigger than LDA′s of flow field in cylinder or that from hot wire wind speed meter,this article puts forward critical crank angle,and points out that the tumble can′t be formed within it.The last cycle′s exhaust has no tumble angle momentum,the charge coefficient has an effect on the angle momentum,and the tumble mathematics expression is more reasonable because of including all of the factors.