高功率密度柴油机主轴承热弹流混合润滑分析

Thermo-Elasto-Hydrodynamic Mixed Lubrication Analysis of Main Bearings for High Power-Density Diesel Engine

基于包含润滑油填充率的Reynolds方程和Greenwood-Tripp微凸峰接触理论,采用质量守恒边界条件,通过使用有限差分法和有限元法联立求解热弹性流体润滑的各控制方程,以某高功率密度柴油机的主轴承为例进行热弹性流体混合润滑研究.通过分析功率密度升高对轴承性能的影响机理,确定需改进的结构参数,考察了油孔位置、椭圆形油孔、轴瓦表面粗糙度和润滑油油品对轴承润滑性能的影响,最终通过合理匹配结构参数使得轴承最小油膜厚度增加了45.04%,,峰值粗糙接触压力减小了76.85%,,平均粗糙摩擦损失功率减小了76.62%,.得到结论:最大剪切率是评价轴承润滑性能的重要指标,表面粗糙度对油膜振荡有遏制作用,油孔对轴承润滑性能具有很大的影响,以及合理匹配结构参数对轴承设计具有重要意义.

Based on the Reynolds function considering lubrication oil filling rate and Greenwood-Tripp asperity con- tact theory, as well as mass-conserving boundary condition, the thermo-elasto-hydrodynamic lubrication controlling equations were solved simultaneously with finite different method and finite element method. Taking a main bearing of high power-density diesel engine as a example to conduct the thermo-elasto-hydrodynamic mixed lubrication study. Through analyzing the mechanism of the influence of power boost on bearing performance, the structural pa- rameters need to be improved were determined. The influences of bearing lubrication performance at different oil hole positions, elliptic oil holes, shell surface roughness and lubrication oil grades were studied. Through reasonable matching the structure parameters, the minimum oil film thickness increases by 45.04%, peak contact pressure de- creases by 76.85%, and average asperity friction loss power decreases by 76.62%. It is shown that the minimum shear rate is an important dynamic indicator to evaluate bearing lubrication property, surface roughness have deterrent effect on oil-film oscillation, oil hole has great effect on bearing lubrication performance. Thus, matching the structural parameters reasonably is significant.