卧式水电机组用径向滑动轴承热弹流特性分析

研究轴颈挠度和瓦块表面热弹变形对卧式水电机组径向滑动轴承静态润滑性能的影响。推导考虑轴颈挠度和轴瓦热弹变形后的油膜厚度表达式;用中心差分法结合ANSYS软件联立求解雷诺方程、能量方程、固体热传导方程、密度方程、黏度方程和轴瓦热弹变形等,得到径向滑动轴承的热弹流润滑(TEHD)特性,并与不计入轴颈挠度及轴瓦热弹变形的油膜动压润滑特性进行比较。结果表明:在考虑轴颈挠度和轴瓦瓦面热弹变形的影响后,油膜压力、温度、厚度沿着轴承宽度中心线的对称特性消失;油膜压力峰值增大,峰值点位置由轴向中心区偏移至出口区;油膜温度峰值增大,最高温度发生在出口区;润滑区内的最小油膜厚度大幅度减小,油膜最小厚度处于出口侧边界附近;轴承润滑流量减小,损耗略有增大;轴承稳态运行时,轴颈偏位角基本一致。

Thermal Elastohydrodynamic Lubrication Performance of Journal Bearing for Bulb Type Hydraulic Power Unit

The effects of shaft deflection,elastic deformation and the thermal distortion of pad face on the thermal hydrodynamic performance of journal bearings for bulb type hydraulic power units were analyzed with full numerical solution.The film thickness equation considering the shaft deflection,elastic deformation and thermal distortion of pad face was proposed.The Reynolds equation,energy equation,solid heat transfer equation,density equation,viscosity equation,elastic deformation of the pad and thermal distortion of the pad face were solved with numerical simulation and software ANSYS,the thermal elastohydrodynamic lubrication(TEHD)performances of the journal bearings were obtained,and compared with the results without consideration of the shaft deflection and deformation of the pad face.The results show that when considering the shaft deflection and deformation of the pad face,the symmetry of hydrodynamic pressure,temperature distribution,minimum film thickness by the middle line of the guide bearing is disappeared;the maximum pressure is increased,the location of the maximum pressure moves from the middle line of the guide bearing to the boundary of the bearing;the oil temperature is increased,the location of the maximum temperature point is in the boundary of downstream side;the minimum film thickness is reduced;the lubrication flow is reduced and the loss is increased;in stability operation,the shaft neck angle is consistent.