中文摘要：

喷油器中空化流特性直接影响燃油的雾化和燃烧。利用CFD-F ire软件,在针阀运动的情况下模拟了喷油器内部从单相流到超空化的过程以及流动特征。数值模拟发现：气泡首先出现在喷孔进口的拐角处,随着流速增加,空化进一步发展,直至贯穿整个喷油器形成超空化,整个流场成为气液两相流。瞬态条件下,针阀运动致使喷孔进口附近压力波动,部分空化与超空化受此影响变得不稳定,这直接影响喷孔出口处燃油的初次雾化。

英文摘要：

Cavitating flow in diesel nozzle affects diesel fuel spray and combustion characteristic.The flow field change model in SAC type nozzle hole was performed by computational fluid dynamics software when needle valve was moving.The results show that the cavitation appears initially at the nozzle hole inlet edge,and it is developed when the diesel fuel increases speed.Ultimately,the cavitation bubble through the nozzle hole forms supercavitation,and the flow field is divided into two-phase flow in nozzle hole.Under unsteady（transient） conditions,needle valve moving results in pressure fluctuation near the inlet of nozzle hole,which influences cavitation and supercavitation.