Experimental Measurement of Oil Film Thickness Distribution in Titling-Pad Thrust Bearings by Ultrasonic Piezoelectric Elements

Introduction Tilting-pad thrust bearings are widely used in high-speed and heavy-load rotor-bearing system. Measurement of the oil film thickness distribution is vital important for understanding bearing's lubrication condition. However, this remains a challenge because the oil film normally locates in the enclosed space and has a very tiny scale. Methods Here, a tilting-pad thrust bearing rig with six pads is built and the ultrasonic methods are used to measure the oil film thickness distribution and further obtain the gesture of the tilting-pad thrust bearing. Eight piezoelectric elements are bonded on the back of one pad of the thrust bearing, making the pad similar as a smart bearing. The oil film thickness of each gauging point is obtained by the characteristic of the reflected sound. Then both the oil film thickness distribution and the gesture of the pad are obtained by fitting the measured values via least square fit. The influences of the vibration, load and rotor speed on the oil film thickness distribution are then investigated. Conclusion The results agree well with the ones obtained by the eddy sensors. This work presents a promising non-invasive method to measure the oil film thickness distribution in tilting-pad thrust bearings.