Effect of rate of viscosity variation on the performance of journal bearings

Variations in viscosity within the film is known to have a pronounced effect on journal bearing performance. Lubricants of the same grade with the same viscosity at a particular temperature and ambient pressure can have different viscosity values at other-temperature and pressures. The effect of rate of viscosity variation due to the changes in temperature and pressure on the performance of an axial grooved journal bearing is the focus of this investigation. Roelands' model on viscosity-temperature pressure relationship of lubricants is adopted. Cavitation modelling with regard to thermal effects and mass conservation are carefully considered. A total THD model with heat transfer within the fluid film and heat dissipation to the ambient through the journal and bush, is utilized. For different rates of viscosity variation with respect to temperature and pressure, comparison of performance parameters and typical temperature distributions are presented.