基于两相流的涡轮增压器轴承油膜特性分析

Analysis on oil film characteristics of turbocharger bearing based on two-phase flow

利用计算流体动力学方法,分析了涡轮增压器半浮动轴承内油膜静力特性,考虑两相流油膜破裂和非牛顿流体润滑油模型,计算分析带轴向贯通油槽的油膜压力和汽化比率分布情况,以及转速、偏心率、润滑油温度和润滑油压力等因素对油膜承载力和摩擦功耗的影响规律。结果表明:温度和转速是影响两相流油膜摩擦功耗的主要因素,分段楔形油膜的摩擦功耗与贯通轴向油槽的位置变化无关,油膜的气穴空化也不会引起摩擦功耗的明显变化;两相流油膜承载力随着偏心率的增加、油温的降低和油压增大而有不同程度的增大,但随转速的变化规律不一致;与此同时,小偏心率、高油压、低油温有利于减轻两相流油膜发生气穴空化的比率。

The static characteristics of inner oil film of turbocharger semi-floating ring bearing were calculated by CFD method.For the inner oil film with axial through grooves,the distribution of oil film pressure and air-phase volume fraction were predicted considering the influence of two-phase flow cavitation and non-Newton fluid.The change rules of oil film bearing capacity and friction power losses with the journal speeds,eccentricity ratio,oil temperature and pressure were also evaluated respectively.The results showed that the uppermost impact factors to friction power losses were oil temperature and journal speed,while the rare relationship with the position of through axial grooves and the cavitation at the nega-tive pressure zone was also found.The oil film bearing capacity can be improved by increasing the eccentricity ratio and oil pressure,or cooling the oil temperature.However,the law of variation with speed up was not consistent.Simultaneously,it was beneficial for alleviating air-phase volume fraction to reduce the eccentricity ratio and oil temperature,or raise the oil pressure.