Thermo-hydrodynamic performance of journal bearings under water contamination of lubricants considering rheological and thermal effects

Journal bearings are susceptible to water contamination due to seal leaks and vapor condensation. Once the lubricant is contaminated by water, its rheological and thermal properties would be affected. Without an appropriate disposal in time, serious faults are likely to occur and the functional life of journal bearings will be significantly reduced. In order to investigate the influence of water contamination on the thermo-hydrodynamic performance of journal bearings, this paper carried out the study on the rheological and thermal properties of lubricants at different water concentrations. Numerical models for viscosity and specific heat capacity were established based on the experimental data. Thermo-hydrodynamic performance of journal bearings under water contamination were then investigated theoretically and experimentally. The results indicate that the lubricant viscosity shows a nonlinear relationship of water concentration, while the specific heat capacity shows a monotonic increase. At high water concentrations, the lubricant exhibits shear thinning behavior. The viscosity changes due to water contamination significantly affect the film thickness, pressure distribution and friction. Temperature rise of the journal bearing decreases with increasing water concentration.