A Study of the Thermohydrodynamic Performance of Steadily Loaded Journal Bearings

Abstract

A comprehensive thermohydrodynamic (THD) analysis of steadily loaded journal bearings has been developed that includes mass conserving cavitation, full solution of the 3-D energy equation in the oil film, heat conduction in the bushing and journal, mixing of hot circulating oil with fresh supply oil and solution of the inverse problem (given the load, find the film thickness). The temperature distribution in the oil film and bushing is found using a coupled approach where the same 3-D energy equation is solved in both the oil film and bushing. With this approach the steady-state problem can be solved without iterations between the thermal solutions in the oil film and the bushing, thereby allowing ready analysis of multilayer bushings. Predictions of the analysis compared very well with measurements reported by Dowson et al. (1). A thermohydro-dynamic study of bearing performance as a function of clearance for a typical automotive bearing revealed that there is an optimum clearance that gives the largest minimum-film thickness. In contrast, isothermal analyses did not show any optimum.