以制冷剂为工作介质的止推气体轴承静态特性分析*

针对离心式压缩机润滑问题,提出以R134a为润滑工质的动压气浮轴承,基于流体润滑的雷诺方程,从制冷剂与空气的流动对比出发,通过理论假设实现气体轴承的建模与分析,采用数值分析对气膜流场进行三维设计计算分析,得到动压止推轴承的气膜厚度分布、气膜压力分布、承载力、功率损耗等特性。结果表明:在相同的情况下以R134a为工质的气体轴承的承载力是空气的50%左右,两者的承载力都随着扇形瓦张角、转速的增大而增大,随倾斜面高度和节距比的增大而先增大后减小,随最小初始气膜厚度的增大而减小;在相同的情况下以R134a为工质的系统的功率损耗是空气的60%左右,两者系统的功率损耗受最小初始气膜厚度和速度的影响最大,转速越高、最小初始气膜厚度越小,两者的功率损耗越大。

Analysis of Static Characteristics of Thrust Air Bearing of Centrifugal Refrigeration Compressor

For the lubrication problem of centrifugal compressors,a dynamic pressure air bearing with R134a as the working medium was proposed.Based on the Reynolds equation of fluid lubrication,starting from the comparison of refrigerant and air flow,the gas bearing was modeled and analyzed through theoretical assumptions.Numerical analysis was used to calculate and analyze the three dimensional gas film flow field,and the gas film thickness distribution,gas film pressure distribution,bearing capacity and power loss of the dynamic pressure bearing were obtained.The results show that the bearing capacity of the gas bearing using R134a as the working medium is about 50% of that using air as the working medium under the same conditions,and the bearing capacity of both is increased with the increase of the fan shaped tile opening angle and rotation speed.The height and pitch ratio are increased first and then decreased,and decreased with the increase of the minimum initial air film thickness.Under the same conditions,the power loss of the system using R134a as the working medium is about 60% of that using air as the working medium.The power loss of the two systems is most affected by the minimum initial gas film thickness and speed.The higher the speed and the smaller the minimum initial gas film thickness,the greater the power loss of the two systems.