Operating Conditions of Multi-Lobe Journal Bearings Under High Thermal Loads

Abstract

The governing equations for the performance prediction of oil film journal bearings in high speed turbomachinery are elaborated. The lubricant temperature and viscosity are admitted to vary in all three dimensions and a possible reverse flow is allowed for. Laminar-turbulent flow transition, thermal groove mixing and film rupture are taken into account with refined models. The computational methods are assembled in a corresponding computer code. A successful verification is accomplished by comparing the theoretical results with recent experimental data. The calculation of the running performance of technically important multi-lobe bearing designs shows the significance of the maximum film temperature as failure criterion in severe operating conditions; flow transition and hot oil carry-over have considerable effects.