A Modified Reynolds Equation with Centrifugal Force being Considered and Its Application to Floating Bush Bearing.

Abstract

A modified Reynolds equation and oil film velocity expressions are derived with centrifugal force acting on the oil film being considered. The equation is applied to the lubricating oil film assumed to be concentric in very high speed journal bearings, and solved for the pressure variation in the axial direction and also across the film thickness. Linked with the cavitation model proposed by Koeneke et al., the lubricating film is theoretically found to rupture near the journal surface toward the bearing end. This axial oil film rupture is shown to reduce the driving torque of the inner film of floating bush bearings at very high shaft speeds, and this analysis can give a reasonable explanation to the phenomenon that the bush-to-journal speed ratio is observed to decrease with shaft speed in actual high speed machinery, though conventional theoretical models could not.