Thermohydrodynamic analysis of journal bearings lubricated with couple stress fluids

Thermohydrodynamic analysis of journal bearings is extended to include couple stress effects in lubricants blended with high polymer additives. Based on the micro-continuum theory, a modified energy equation is derived and then is simultaneously solved with the heat transfer equation as well as the modified Reynolds equation. The effects of couple stress on the key performance of a finite journal bearing, such as maximum temperature, shaft temperature, load capacity, friction force, friction coefficient, and side leakage flow, are presented. The results have shown that lubricants with couple stresses, compared with Newtonian lubricants, not only yield an obvious increase in load capacity and decrease in friction coefficient, but also produce a lower bearing temperature field. Thus it can be concluded that the lubricant with couple stress does improve the performance of journal bearings.