Axial Oil Film Rupture in High Speed Bearings Due to the Effect of the Centrifugal Force

The two-dimensional steady-state Navier-Stokes equation and the continuity equation are applied to the lubricating film assumed to be concentric in journal bearings operating at very high speeds. The equations are numerically solved for the pressure variation in the axial direction and also across the film thickness with the centrifugal force being considered to act on the lubricant film due to high rotational speed of the journal. Linked with a new cavitation model proposed, the lubricant film is theoretically found to rupture near the journal surface toward the bearing end. This axial film rupture (AFR) is shown to reduce the driving torque of the inner film of floating bush bearings at very high shaft speeds, and some phenomena observed in the operation of floating bush bearings can be explained with this model.