Enhancement of water lubrication in a rubber journal bearing by small-quantity oil

In this work, the idea of water lubrication enhanced with a small quantity of oil was tested for the first time in a rubber journal bearing. A small quantity of silicone oil was supplied to an eight-groove rubber bearing through a small nozzle, aiming to improve the lubrication of the bearings under short-term severe working conditions. The results demonstrated that the addition of small quantities of silicon oil can significantly reduce friction, with the coefficient of friction (COF) at certain speeds being lower than that achieved with either pure water or pure oil. If the oil was given under frequent and small-quantity supply, a smaller time interval of oil supply has little impact on friction reduction. Moreover, a simple method based on the Stribeck curve was proposed to roughly predict the COF reduction of water-lubricated journal bearings with a small quantity of oil supply at low speeds. Additionally, computational fluid dynamics (CFD) simulations provided insights into the migration/diffusion of injected oil within the bearing, revealing a correlation between the oil-side leakage and the COF.