Motions of Air Bubbles Trapped in Grooved and Plane Journal Bearings of Operating Fluid Dynamic Bearings

We investigated the motion of air bubbles trapped in grooved and plane journal bearings of operating fluid dynamic bearings (FDBs) by using the finite volume method and the volume of fluid method. The motion of a trapped air bubble in grooved journal bearing is mostly determined by surface tension and the pressure difference due to the wedge effect of the groove. Also, the motion of trapped air bubbles in plane journal bearing is mostly determined by surface tension and the Coutte flow. A novel design of FDBs was finally proposed to expel the air bubbles trapped in grooved journal and plane journal bearings out of operating FDBs.