Fluid inertia and energy dissipation in turbocharger thrust bearings

The present study introduces a new transient modified Reynolds equation by considering a detailed model to represent multigrade engine oils. Elastic effects introduced by long polymeric chain additives are studied. This thin film equation also accounts for well known rheological effects such as the viscosity dependence on temperature and shear rate. The application of this model to turbocharger (TC) thrust bearings is presented and includes the consideration of fluid inertia. Performances predictions of a typical TC thrust bearing are compared to experimental data obtained on a test rig. Rheological parameters are varied to determine the influence of current engine oils on the phenomenon of turbo lag.