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 nonparallel 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, while 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.