Experimental research on tribological and vibration performance of water-lubricated hydrodynamic thrust bearings used in marine shaft-less rim driven thrusters

Abstract

Aiming at the demand of marine shaft-less rim-driven thrusters(RDTs) for high load capacity, long life, low friction and low vibration water lubricated hydrodynamic thrust bearings(WLHTBs), three types of WLHTBs were designed and manufactured: pivot-supported, rubber-supported and fixed pads bearings. A series of experiments were carried out to study their tribological and vibration performance. Axial force, friction torque, axial displacement of the thrust collar, water temperature and vibration characteristics under different working conditions were acquired by a load cell, a torque meter, 4 proximity sensors, 2 thermometers and 3 B&K pulse sensors during a planned 200 h’ test for each bearing. The experimental results indicate that pivot and rubber-supported bearings have good lubrication and load carrying properties under different conditions. With the rotation speed of the thrust collar increases from 100 to 600 r min−1, the friction coefficient of both bearings is lower than 0.06 under the specific pressure of 0.1 MPa, and reduces similarly to lower than 0.01 under 0.5 MPa. The vibration acceleration amplitude of the rubber-supported WLHTB in X, Y and Z directions are all less than the value of pivoted and fixed pads ones under same speed and load condition. After 200 h of test, the average height and mass loss of the pivot and rubber-supported pads of each WLHTB have only reduced 35 µm/0.0232 g and 42.4 µm/0.0296 g respectively. On the contrary, the performance of the fixed pads bearing is the worst. Under the specific pressure of 0.5 MPa condition, the friction factor increases to 0.2 when the speed reaches 600 r min−1, and the outlet cooling water temperature increases to 70 °C in 20 min. The thrust collar is damaged and the pads’ polymer surfaces are burnt. The experimental research results provide an important reference for the design of WLHTBs for RDTs.