考虑不同加速工况的滑动轴承的启停性能分析

Analysis of Start-Stop Performance of Journal Bearing Considering Different Acceleration Conditions

滑动轴承的摩擦磨损主要发生在启停阶段。为了研究启停工况下的滑动轴承的摩擦学性能,建立一种面向径向滑动轴承的混合润滑数值分析模型。采用质量守恒边界条件的雷诺方程求解流体压力,采用Greenwood和Tripp接触模型预测固体表面接触,而通过Johnson载荷分配概念将润滑模型和接触模型联系起来,从而实现对滑动轴承在启停工况下从混合润滑过渡到动压润滑的摩擦学行为分析。利用该模型,研究轴承系统在启停阶段从边界润滑、混合润滑到动压润滑演化过程中的摩擦学性能;以径向滑动轴承系统为例,结合不同的轴承转速变化函数,分析轴承加速对轴承启停性能的影响;同时研究工作工况、润滑油温度、轴承的结构参数对轴承启停性能的影响。结果表明:轴承启动加速度在合理范围内越大越好,能使轴承更快进入动压润滑;较高的转速、较低的润滑油温度和较大的径向轴承间隙能使轴承拥有更好的启停性能。

The friction and wear of journal bearing mainly occurs in the starting and stopping stage.In order to study the tribological performance of journal bearing under start-up condition,a numerical analysis model of mixed lubrication for journal bearings was developed.Reynolds equation with mass conservation boundary condition was used to solve the fluid pressure,Greenwood and Tripp contact model was used to predict the solid surface contact,and Johnson load distribution concept was used to connect the lubrication model and contact model,so as to realize the tribological behaviors of journal bearings from mixed lubrication to hydrodynamic lubrication under start-up and shut-down conditions.By this developed model,the starting and stopping performance of journal bearing system was analyzed under three different lubrication conditions,the boundary lubrication,mixed hydrodynamic lubrication and hydrodynamic lubrication.With the journal bearing system as an example,by combined with different functions of the bearing speed,the influence of the acceleration performance of the bearing on the start-up performance of the bearing was analyzed.The effects of working conditions,oil temperature and bearing structure on the start-up performance of the bearing were studied.The results show that the larger starting acceleration of the bearing can help the bearing enter the hydrodynamic lubrication faster.Higher rotating speed,lower lubricating oil temperature and larger bearing clearance can make the bearing have a better performance in start-up stage.