Abstract: To more effectively reduce the cavity temperature of high-speed angular contact ball bearings for high-power high-speed electric spindles,the effect law of oil-air lubrication containing graphene on the heat flow characteristics of the bearing cavity was analyzed.Based on the conservation equations of fluid mechanics,a mathematical model of thermal flow analysis for the gas-liquid-solid three-phase flow formed by the compressed gas,lubricating oil and graphene particles in the cavity of a high-speed angular contact ball bearing was established.The formation conditions of graphene lubricant annular flow in the oil-gas passage at different velocities of compressed gas state,the velocity of graphene lubricant flow field in the bearing cavity and the relationship between graphene particle distribution and bearing cavity temperature field were numerically simulated.The results showed that an annular flow of graphene lubricant would be formed in the oil-gas channel as a way to achieve good lubrication of the contact ball bearing cavity when the ratio of graphene lubricant velocity to compressed gas velocity was 1:10;the distribution of graphene in the bearing cavity was affected by both centrifugal force and high speed spin of the ball,and the temperature was lower in the area having more dense of graphene particles;the greater the graphene lubricant flow rate in the ball to inner ring contact area,the higher the surface heat transfer coefficient,resulting in good heat dissipation,which provided theoretical basis for graphene oil-air lubrication to better reduce the temperature of high-speed angular contact ball bearings and ensure the normal operation of the bearings.

Key words: oil-gas lubrication, graphene, angular contact ball bearings, three-phase flow

摘要： 为更有效地降低大功率高速电主轴用高速角接触球轴承腔温度,对含石墨烯的油气润滑影响轴承腔热流特性的规律进行分析。基于流体力学守恒方程,建立了高速角接触球轴承腔体内压缩气体、润滑油和石墨烯颗粒形成的气液固三相流热流分析数学模型。通过数值模拟分析了不同速度压缩气体状态下油气通道中的石墨烯润滑油环状流形成条件、轴承腔内石墨烯润滑油流场速度,以及石墨烯颗粒分布与轴承腔温度场的关系。结果表明,石墨烯润滑油速度与压缩气体速度之比为1∶10时,油气通道中会形成石墨烯润滑油环状流,使高速角接触球轴承腔具有良好的润滑效果;高速运转工况下,轴承腔内石墨烯的分布状态同时受离心力与滚珠高速自旋的影响,而且石墨烯颗粒分布越密集,该区域的温度越低;石墨烯润滑油在滚珠与内圈接触区域流速越大,表面换热系数越高,该区域散热越快,为石墨烯油气润滑更好地降低高速角接触球轴承温度、保障轴承正常工作提供了理论依据。

关键词: 油气润滑, 石墨烯, 角接触球轴承, 三相流