集成弹流润滑理论及CFD方法的轴承热特性

Thermal characteristics for bearing combined EHL theory with CFD method

为能准确预测传动系统内部角接触球轴承在喷油润滑方式下的热特性,通过建立轴承热弹流润滑(EHL)模型,获得球体与滚道微观接触界面间的载荷及摩擦因数,并采用局部生热法计算生热量;应用计算流体动力学(CFD)方法建立轴承油气两相热流耦合模型,研究湍流模型及流体域边界条件的设置,分析喷油速度、喷嘴位置及含气率对轴承内部传热性能的影响。结果表明:结合热弹流润滑理论及CFD方法可预测轴承在不同工况条件、润滑参数、几何参数下的最佳喷油速度、喷嘴位置及含气率;喷油速度为5 m/s时,轴承内部最高温度较其他喷油速度降低了4.40%;喷嘴位置在轴承下方时,轴承内部最高温度较其他位置降低了4.30%;含气率为15%时,轴承内部最高温度较其他含气率降低了1.57%。

In order to accurately predict the thermal characteristics of angular contact ball bearing in the transmission system under spray lubrication,the bearing thermal elastohydrodynamic lubrication(EHL)model was established,and the micro-contact interface load and friction coefficient between the raceway and ball were obtained.On the basis,heat generation was calculated by using the local generation.Computational fluid dynamics(CFD)method was used to establish a coupled oil-gas two-phase flow model for angular contact ball bearings,including the choice of turbulence model and fluid domain boundary conditions.Furthermore,fuel injection speed,nozzle position and gas fraction were analyzed.Results showed that the application of CFD method with accurate heat generation calculated by the thermal EHL theory could predict the optimal injection speed,the nozzle position and gas fraction of the bearing under various operating conditions,lubrication parameters and geometric parameters.When the injection speed was 5 m/s,the maximum temperature of the bearing chamber was decreased by 4.40%compared with other injection speeds.When the nozzle position was below the bearing axis,the maximum temperature of the bearing chamber decreased by 4.30%compared with other positions.When gas fraction was 15%,the maximum temperature of the bearing chamber was improved by 1.57%compared with other gas fraction.