耦合CFD径向微动分析的航空齿轮泵轴承起动瞬时润滑特性研究

Research on Aero-Gear Pump Journal Bearings Start-Up Transient Lubrication Characteristics with Radial Micro-Motion Analysis Coupled CFD

为研究处于动态起动过程中航空齿轮泵齿轮轴-轴瓦隙内油膜的润滑问题,在齿轮泵CFD仿真模拟的基础上,基于齿轮轴所受载荷与轴承间隙起动混合支撑作用的动力学关系,实现了耦合CFD的轴心径向微动分析。对处于齿轮泵瞬态场影响下的滑动轴承起动瞬时润滑特性及接触行为进行了数值分析。仿真结果表明:齿轮泵瞬态场变化产生的载荷波动对轴心微动产生的影响在起动低偏心阶段更为明显,造成的最终静平衡位置在不同方向上差异为0.43%和7.29%;润滑界面微观粗糙度的影响存在于起动高偏心阶段;在泵进口压力不变的条件下,其出口压力的增大不改变固体接触力的作用时间,但会使接触现象加剧;齿轮泵稳定工作转速的增大会减小接触作用时间,并且使不同方向接触力的差值减小;齿轮泵工况改变对于最小油膜厚度的影响相似于轴心轨迹,当出口压由3.02MPa增至9.1MPa时,最小膜厚减小率最大可达26.32%和101.43%。

In order to solve the lubrication problem of oil film inside an aero gear pump gear-shaft/bearing gap during dynamical start-up process,on the basis of gear pump CFD simulation,axis center radial micro-motion analysis coupled with CFD has been carried out based on dynamic relationship between gear shaft load and lubrication gap mixed supporting effects.Numerical analysis was carried out to investigate the start-up transient lubrication characteristics and contact behavior of journal bearings under gear pump transient field influence.The results show that:the load fluctuation caused by gear pump transient field variation has a more noticeable effect on pump shaft motion at low eccentricity position during startup than other cases.Note that difference of final static equilibrium position caused by load fluctuation are 0.43%and 7.29%on different directions.Besides,the influence of micro-characteristic on surfaces mainly exists in high eccentricity state during startup.Under the same condition of inlet pressure,increase trend of pump outlet pressure has no change to asperity contact time but makes contact more serious.It yields a decrease in contact time and difference between different directions contact forces as rotate speed increases.Regarding for the oil film characteristics in lubrication gap,the variation of minimum film thickness under different pump operating conditions is similar to center trajectory.When the outlet pressure increases from 3.02 MPa to 9.1 MPa,the maximum reduction rate of the minimum film thickness approaches 26.32%and 101.43%.