Lubrication mechanisms and performance of micro-grooved water-lubricated bearings under cavitation–inertia coupling

Surface micro-grooves can effectively improve the lubrication performance of water-lubricated bearings, but the coupling mechanism between groove-induced cavitation and fluid inertia remains unclear. In this study, fluid inertia was further incorporated into a previously developed cavitation framework, and a coupled computational model was established by considering cavitation, fluid inertia, elastic deformation of the bearing liner, and surface roughness. The influence of micro-grooves on the lubrication performance of water-lubricated bearings was analyzed at both the single-groove and full-bearing levels. The results show that cavitation weakens local pressure build-up and reduces the load-carrying capacity of the bearing, whereas inertia enhances the local hydrodynamic effect near the groove edges through inertia-induced local flow redistribution. Under coupled conditions, cavitation suppresses the lubrication gain brought by inertia to some extent. Further parametric analysis indicates that the lubrication performance of micro-grooved water-lubricated bearings is sensitive to both operating and structural parameters. Within the present model and the investigated operating range, when the eccentricity ratio is 0.2, the micro-groove increases the bearing load-carrying capacity by ∼5.6%, and an appropriate combination of groove parameters helps achieve both load enhancement and friction reduction. The results indicate that the lubrication enhancement provided by micro-grooves is fundamentally governed by the competition between cavitation-induced degradation and inertia-related hydrodynamic enhancement, and may provide useful guidance for groove parameter optimization and engineering design.