Analysis of Water-Lubricated Journal Bearings Assisted by a Small Quantity of Secondary Lubricating Medium with Navier–Stokes Equation and VOF Model

Due to the low viscosity of water, water-lubricated bearings are susceptible to significant wear and noise in demanding operating conditions. It has been demonstrated that a small quantity of secondary lubricating medium can improve the lubrication performance of water-lubricated contact surfaces and achieve the purpose of temporary risk aversion. As a further step, the feasibility of the proposed idea is experimentally validated on a water-lubricated bearing test bench. A numerical model that couples the N–S equation and the VOF model is then developed to investigate the behavior of the flow field lubricated by pure water and water with a small quantity of the secondary lubricating medium. This model provides the predictions of important quantities such as the load-carrying capacity, the secondary lubricating medium volume fraction and the contact pressure under different lubricated conditions. The results show that the secondary lubricating medium can enter into the contact region and improve the lubrication performance of water-lubricated bearings, especially at lower shaft rotational speeds. Therefore, the feasibility of our proposed idea is verified, which provides a promising approach to reduce the wear and friction of water-lubricated bearings when they encounter short-time severe working conditions.