TRANSIENT THERMOELASTOHYDRODYNAMIC STUDY OF TILTING-PAD JOURNAL BEARINGS - APPLICATION TO BEARING SEIZURE

Nowadays, tilting-pad journal bearings are used under more and more se verely demanding operating conditions. Three limits of safe operation were defined (Leopard, 1976): the hydrodynamic limit, the mechanical l imit and the thermal limit. The purpose of this study is to determine the hydrodynamic limit of safe operation during start-up for a tilting -pad journal bearing. During start-up, the rapid increase of the tempe rature in the bearing solids leads to the thermal expansion of both th e pads and the shaft. The operating bearing clearance decreases and, w hen it tends toward zero, seizure occurs. The evolution of the main ch aracteristics (temperature, pressure, film thickness and displacements ) versus time is analyzed in the case when a seizure occurs.