针阀关闭时刻柴油机不同喷孔内流场的计算

基于开源软件OpenFOAM定义两种连续的网格运动使针阀完全关闭，分三步数值模拟针阀关闭时刻喷孔内的瞬态流场，模拟结果与S ．Jollet试验结果基本吻合。在此基础上研究喷孔结构参数对孔内流场的影响，计算结果表明，随着孔径的增大，喷孔内残余燃油内部有气泡形成；喷孔长度越短，喷孔内残余燃油内部的空气体积越大，形成的气泡越靠近压力室；K系数的减小有利于喷孔内气泡的产生。

Calculation of Internal Flow Field in Different Nozzle Orifices of Diesel Engine at Needle Value Close Timing

A new algorithm consisting of two kinds of continuous mesh‐moving was proposed to make the needle close com‐pletely based on the open source software Open FOAM and the transient internal flow field in nozzles was numerically simulated by three steps .The simulation results coincided with the experimental results of S .Jollet .The effects of nozzle structure pa‐rameters on the flow field inside the hole were further studied .The results show that the bubble in residual fuel of nozzle occurs with the increase of nozzle diameter .The shorter nozzle orifice length leads to larger bubble volume inside residual fuel and closer distance of bubble with pressure chamber .Besides ,the decrease of K‐factor is beneficial to the formation of bubbles .