Numerical study on the static and dynamic performance of worn water-lubricated journal bearings considering cavitation

Abstract

The inevitable wear of water-lubricated bearings (WLBs) during operation affects their lubrication properties. The existing studies mainly focus on the tribological performance and wear rate of WLBs, while little has been reported on the static and dynamic properties of bearings subjected to wear, especially regarding stability assessment. The novelty of this study is to integrate the wear morphology with the mass-conservation cavitation algorithm to reveal the influence of different wear morphologies on the static and dynamic properties and stability of WLBs, and to quantify the influence of the cavitation effect on the prediction of lubrication performance. Therefore, this study proposes an elastohydrodynamic lubrication (EHL) model for WLBs, considering cavitation effects and bush wear. The equations are discretized using the control volume method (CVM) and solved using the Fischer-Burmeister-Newton-Schur (FBNS) method. The model's accuracy is verified by comparing the experimental data with the published literature. On this basis, the effects of cavitation, wear offset angle, and wear depth on the static and dynamic properties of WLBs are investigated. The results show that the cavitation effect can improve the load-carrying performance of WLBs, reduce the frictional coefficient, and increase the stiffness and damping coefficient. The bush wear may have a detrimental impact on WLBs. When the wear depth is particularly substantial, it can lead to significant inaccuracies in the Reynolds boundary conditions. Furthermore, a negative wear offset angle enhances the hydrodynamic effects and decreases the fractional coefficient, resulting in a more pronounced impact on the stiffness and damping in the vertical direction. Conversely, the positive wear offset angle has the opposite effect. This research offers a practical approach for predicting the static and dynamic performance of worn WLBs and valuable ideas for enhancing the system's stability and design.