不同进口压力下柴油机非对称喷嘴内部流动特性的数值分析

Numerical Analysis on Internal Flow Characteristics of Asymmetric Nozzle for Diesel Engine Under Different Inlet Pressures

采用流体动力学欧拉多相流模型,模拟了不同进口压力下柴油机喷油器非对称喷嘴内部流动特性,研究了喷嘴各孔出口处气相体积分数和质量流率分布特性。结果表明:喷嘴内部形成了均匀的雾化场,喷嘴出现空化的气相体积比和压力差上升速度都表现为孔1孔、5孔、2孔、3孔、4孔逐渐降低变化,并且空化现象基本都出现在转角上部。喷嘴各孔质量流率均随进出口压力差表现出单调增加的变化规律,之后趋于一定的稳定。在进口压力30 MPa下,压力增大后将会促进质量流率的升高;在80 MPa的进口压力下,质量流率不会发生显著改变;随着进口压力达到160 MPa,质量流率处于一个恒定状态。

We simulate the internal flow characteristics of asymmetric nozzles of diesel injectors with different inlet pressures by using a hydrodynamic Euler multiphase flow model. The distribution characteristics of gas volume fraction and mass flow rate at orifice of nozzle are studied. The results show that a uniform atomization field is formed inside the nozzle, and the volume ratio of the gas phase and the rising speed of pressure difference in the cavitation of the nozzle all show a gradual decrease and change in holes 1, 5, 2, 3 and 4, and the cavitation phenomenon basically appears in the upper corner. The mass flow rate of each hole of the nozzle increases monotonously with the pressure difference between inlet and outlet, and then tends to be stable. At the inlet pressure of 30 MPa, the increase of pressure will promote the increase of mass flow rate. At the inlet pressure of 80 MPa, the mass flow rate does not change significantly. With the inlet pressure reaching 160 MPa, the mass flow rate is in a constant state.