空间热泵气体静压止推轴承静动态性能研究

Static and Dynamic Characteristics of Externally Pressurized Thrust Bearings for Space Heat Pump

针对应用于空间热泵压缩机的氟利昂气体静压止推轴承的设计,采用动网格仿真方法对R134a气体静压止推轴承的静态和动态性能进行研究,通过实验对单孔进气止推轴承动网格仿真结果进行对比,验证了动网格仿真方法的有效性。结果表明:减小气膜厚度和增大供气压力可有效增大止推轴承的承载力,在气膜厚度较小时,通过减小气膜厚度所带来的承载力增幅很小;止推轴承的静态刚度随着供气压力增大而增大,存在一个最佳的气膜厚度使静态刚度达到最大值;随着外界激励频率的增大,止推轴承的动态刚度增大,阻尼系数减小,最后趋近于0;在相同的激励频率下,动态刚度和阻尼系数随着气膜厚度的增大而减小。

Targeting the design of the externally pressurized thrust bearings used in space heat pump compressors,the static and dynamic characteristics of an externally pressurized thrust bearing lubri-cated with R134a gas were numerically studied through dynamic mesh method.The validity of the numerical method was verified experimentally.The study results show that a higher load capacity was obtained by reducing the bearing clearance or increasing the supply gas pressure.However,when the bearing clearance was very small,a large reduction of bearing clearance only brought a slight increase in load capacity.The static stiffness increased with the increase of the supply gas pressure and there was an optimal bearing clearance to maximize the static stiffness.As the excita-tion frequency increased,the dynamic stiffness increased and the damping coefficient decreased.At the same excitation frequency,the dynamic stiffness and damping coefficient both decreased with the increase of the bearing clearance.