Effect of Cavitation on the Performance of Journal Bearings Lubricated with Non-Newtonian Lubricant

Journal bearings work under severe conditions of speeds and loads are far away from working at Newtonian condition due to the high shearing rate of the fluid in this case with cavitation at its divergent zone. The main goal of the present work is to study the journal bearing performance considering combined effects of nonlinearity behavior of the working fluid, cavitation, and the bearing liner elasticity. For this purpose, a finite length cylindrical journal bearing working with non-Newtonian lubricant modeled and analyzed numerically considering the effect of parameters. The analysis was implemented by solving the main governing equations using a suitable prepared computer program. The flow of lubricant assumed laminar, incompressible, and isothermal. Lubricant shear stress assumed to vary with a shear rate according to the power law with index coefficient (λ) varies from 0.7 to 1.3 while the cavitation effect included by implements Elrod's cavitation algorithm (ECA). The elastic deformation is considered by calculating the radial component of the bearing liner elastic deformation which is a function of the elasticity coefficient κ. Different parameters investigated in static analyses and the numerical model validated by comparing the results of pressure and density ratio obtained in the present work with that obtained by Ye et al., (1994) and they are found in a good agreement. The results obtained showed an increase in oil film pressure and the load carried by the bearing while the coefficient of friction decreases when the bearing lubricated with a non-Newtonian lubricant of a higher index.