Hydrodynamic Analysis of a Two-Lobe Bearing Lubricated with a non-Newtonian Fluid: Effects of Geometric and Rheological Parameters on Operating Characteristics

Abstract

In the context of hydrodynamic lubrication, this paper investigates the contribution of the aspect ratio R/L to the static performance of two-lobe bearings, by incorporating the non-Newtonian rheological response of the lubricant modeled by the power law. The Reynolds equation is reformulated to incorporate fluid rheology and solved numerically using the finite difference method to determine the pressure profile within the lubricant film. The analysis focuses on the cross-impact of the aspect ratio, the power law index n, and the eccentricity ratio ε, on key parameters such as film thickness, pressure, load-carrying capacity, attitude angle, frictional force and coefficient, as well as the side leakage. The results indicate that film thickness is only marginally affected by the R/L ratio, but is highly sensitive to the lubricant's rheological properties, especially in high shear zones. A reduction of R/L or an increase of n improves the hydrodynamic support. Furthermore, shear-thickening fluids promote the load-carrying capacity and tribological efficiency, while long bearings exhibit increased sensitivity to leakage effects.