Observation and Prediction of Cavities in a Lubricant Between Non-Parallel Disks in Relative Rotation

Observed and predicted cavity shapes in a lubricant between two disks are presented. The geometry is similar to that of a thrust bearing or a face seal having non-parallel rotating surfaces. Photographs of cavitated regions are shown and compared with predictions of cavity shapes obtained by an approximate calculation method analogous to the short bearing analysis used for journal bearings. The calculation and the experiment show steady state cavities that are symmetric about the maximum gap thickness. For small angles of disk inclination a single exterior cavity is seen and for larger values of inclination both an interior and an exterior cavity are present. The predicted cavity shape in a given case is a function of the disk inclination, the lower bound pressure for the oil film and rotor speed. General agreement on the cavity shape is obtained between theory and experiment.