Numerical investigation of oil spray lubrication for transonic bearings

To explore the gas-phase characteristics of transonic bearings and the impact of nozzle parameters on the oil spray lubrication for transonic bearings, the article took angular contact ball bearings as the research object, simulated the state of the transonic gas-phase mediums of rolling bearings using fluid dynamics method, investigated the pressure and velocity characteristics of the airflow in bearing rings, and confirmed the optimal oil injection location. A gas–liquid two-phase flow model was established based on the law of gas-phase flow, the influences of oil spray lubrication parameters, in particular the nozzle angle and nozzle diameter, on the volume fraction of oil in bearing chamber were discussed and verified through experiment. Research results revealed the pressure and velocity characteristics of the gas-phase flow of transonic bearings; it was obtained that the air pressure at 0.25 dimensionless radial axis on small end face of the bearing was small, which was beneficial to lubricating oil into the bearing chamber. The average speed of both end faces increased approximately linearly as DN rose, whereas the speed boost in axial direction was relatively gentle. A higher DN value made it more difficult for the flow around the bearing to carry oil into the bearing ring. When the value of DN equaled to 3.0 × 106, the angle between nozzle axis and inner ring was 30°, and the nozzle had a diameter of 1.5 mm, the oil in bearing chamber showed the highest volume fraction, which was beneficial to the formation of oil film, and produced the best oil spray lubrication effect.