Transient Thermoelastohydrodynamic Study of Tilting-Pad Journal Bearings—Application to Bearing Seizure

Nowadays, tilting-pad journal bearings are used under more and more severely demanding operating conditions. Three limits of safe operation were defined (Leopard, 1976): the hydrodynamic limit, the mechanical limit 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 temperature in the bearing solids leads to the thermal expansion of both the pads and the shaft. The operating bearing clearance decreases and, when it tends toward zero, seizure occurs. The evolution of the main characteristics (temperature, pressure, film thickness and displacements) versus time is analyzed in the case when a seizure occurs.