Characteristics of an Oil Squeeze Film

Abstract

This paper presents both theoretically and experimentally determined characteristics of an oil squeeze film. In the experimental arrangement, an oil film was contained within two plane surfaces having only normal oscillatory relative motion. The effects of initial oil film thickness, peak to peak amplitude, and frequency of oscillation were measured. A finite difference treatment gave theoretical oil pressure fields and forces for any specified normal velocity. Comparisons were made between the pressure measured at one position and its theoretical counterpart over an oscillatory cycle. Subzero oil film pressures were measured. A steady state (in addition to the dynamic) oil film force was identified, whose magnitude and direction depend on the mean oil film thickness, oscillatory amplitude, and frequency. A region of unstable behavior was found. Theory agreed reasonably with practice, but over estimated some oil film pressures and gave time histories which exhibited phase differences with the measured counterpart. These differences were not explained by including the measured pad misalignment in the theoretical model. Further extensions to the theory are suggested.