航空发动机轴承腔内两相流动数值模拟

Numerical Simulation of Two-Phase Air/Oil Flow in Aero-engine Bearing Chamber

主轴承腔作为航空发动机润滑系统油气两相流的重要区域,腔内的高温高压及其回油特性对润滑系统的性能都有很大影响。利用VOF数值计算模型对某航空发动机轴承腔简化模型内油气两相流进行数值计算,将两相之间表面张力作为源项添加到动量方程中,并依据实际情况添加壁面黏附模型,计算结果与现有实验数据符合良好。分析几种工作参数下润滑油相界面的差异及其原因,研究腔压及回油油气体积比随转子转速及润滑油流量的变化规律。结果表明:腔内的压力沿周向在出口处附近较低,并且随着转子转速或润滑油流量的增加而增大;回油孔出口处油气体积比随润滑油进口流量增加而增大;当润滑油进口流量一定时转子转速增大不利于回油。

Bearing chamber as the interface between the oil and the secondary air flow is one of the most important components in aero-engine lubrication system. The high temperature and high pressure characteristic and the scavenge ability have a great impact on the performance of lubrication system. Two-phase flow in a simplified bearing chamber was simulated by VOF numerical model. Surface tension between two phases was added into the momentum equation as the source item. Based on the real condition, the model included the wall adhesion model. The simulation results are in line well with the existing experimental data. The interfaces between oil and air for a wide range of engine relevant conditions and the differences were analyzed, the effect of rotor speed and the oil inlet flow rate on the pressure in chamber and the scavenge oil volume ratio to air was investigated. The results show that the pressure in chamber is low in the outlet, and it increases with the increase of rotor speed and oil inlet flow rate. The scavenge oil volume ratio to air increases with the increase of oil inlet flow rate. The increase of rotor speed is not helpful to the scavenge oil when the oil inlet flow is constant.