Investigation on the transient asperity contact behaviours of water-lubricated bearing under start-stop cycle

The main purpose of this study is to assess the transient lubrication performances and dynamic behaviours of water-lubricated bearings during start-stop cycle based on the numerical prediction. The transient mixed lubrication model coupled with dynamic equation during start-stop cycle is established, in which the asperity contacts, and elastic deformation are considered. The effectiveness of the present numerical simulation is verified by the comparisons with the published test results. Based on the numerical study, the transient asperity contacts and dynamic behaviours under different radial clearances and acceleration time are revealed. The results demonstrate that at the initial and end time during the start-stop cycle; the asperity contact is more serious. That is because the hydrodynamic water film is not quite formed at the initial start-up period and at the shut-down period the hydrodynamic water film is going to disappear. As a result, during this period, the external load is mainly shared by the contact load. Especially when the radial clearance is small, the asperity contact is more serious. In addition, under longer acceleration time, the journal trajectory shows better consistency of the start-up and shut-down conditions.