Flow structure in a flooded ball bearing

The flow structure in the confined space between the outer ring, the cage and the balls of a bearing is investigated using a large scale model allowing to perform visualizations, by tracer and dot-paint techniques, and velocity measurements, by Laser Doppler Velocity (LDV), through the transparent rotating outer ring. The visualization results show, in the region between two consecutive balls, the existence of a reversed flow on the cage surface resulting from the aspiration and blowing effect of the rotation of the balls in their cage housings. Systematic measurements of azimuthal velocities in different cross-sections of the gap confirmed the qualitative visualziation findings in laminar flow. For turbulent flow the results show that the extension of the reversed flow region is reduced and the reversed velocities are proportionally smaller as compared to the laminar case.