四气门柴油机进气门出口流速的分布

对四气门柴油机在两个进气道单独和同时开启的情况下，利用热线风速仪测量进气门出口全圆周速度分布，并通过动量矩流率的计算，分析了两个进气道气流相互影响的变化规律及其主要影响因素。结果表明，在进气过程中，两个进气道之间的气流相互影响，造成了两进气门出口速度的再分配，进而导致了缸内气流绕气缸轴线动量矩流率的变化。动量矩流率的总量与两气道单独开启时相比有明显减少，这是两气道的组合涡流比小于单独气道涡流比的主要原因。两进气道之间的干扰程度与作用结果取决于气道本身的结构形状和相对位置。

Study on Velocity Distribution of Air Flow around Intake Valves

In this paper, the velocity distributions of air flow around the intake valves were measured by means of hot wire annemometer under the conditions of the two intake valves opening alternatively and simultaneously and the interaction between two intake ports was analyzed by calculating the change of momentum flux rate. The results show that the two intake ports of the four valve diesel engine were interacted on each other during induction process, which caused the redistribution of intake air velocity and the momentum change around the cylinder axis . The reduction of total momentum flux rate around the cylinder axis is the main reason of swirl ratio decreasing when the two intake valves opening simultaneously compare with that of two intake valves opening alternatively. The effects of interaction depend on port structure and relative position between the two ports.