Modeling of combustion engine bearing lubrication

Abstract

This work represents an effort to achieve greater understanding on the lubrication of engine journal bearings and develop a model which can be used in future work for the optimization of load carrying capacity and minimization of frictional power loss. In a first step a model is presented which include dynamic loading, cavitation, non-Newtonian lubrication and groove geometry. The model is incorporated in a commercial multiphysics software (COMSOL). Cavitation and non-Newtonian lubrication are complex phenomena which require model simplifications. Cavitation model simplification has been chosen after evaluation of solutions found in literature while a new model one has been proposed for non-Newtonian lubrication. The simulation model for journal bearings has then been used to analyze bearing performance under geometrical and oil parameters variation. Main results include that typical oil definition with viscosity values at high and low shear rates is insufficient and that higher eccentricity in operating conditions helps bearing stability against perturbations.