Characterization of High-Power Turbomachinery Tilting Pad Journal Bearings: First Results Obtained on a Novel Test Bench

Tilting pad journal bearings are commonly used in turbomachinery for their stability at high rotational speeds. The behaviour of the bearings influences the dynamics of the rotor, so the determination of its stiffness and damping coefficients is of fundamental importance. This is often done experimentally by applying dynamic loads to the bearing and measuring the rotor/stator relative displacement. A novel experimental apparatus has been realised, in the frame of a collaboration between the Department of Civil and Industrial Engineering of the University of Pisa, GE Oil&Gas and AM Testing, to test bearings with diameters from 150 to 300 mm, with peripheral speeds up to 150 m/s, static load up to 270 kN, single tone or multitone dynamic loads up to 30 kN and frequencies up to 350 Hz. It includes very complex mechanical, hydraulic, electrical and electronic systems and requires about 1 MW of total power. In this work the first results of the static and dynamic characterization of a high performance tilting pad journal bearing of the rig are reported. Tests are typically conducted in steady conditions monitored by several sensors. Nonetheless some transient phenomena have been observed.