Experimental Study of Cavitation in an Oscillatory Oil Squeeze Film

Abstract

A displacement-controlled parallel-plate squeeze film test apparatus was designed and built to study the cavitation of oil films. Simultaneous pressure measurement and high-speed photography were conducted in the experiment. The study was aimed at comparing the measured results with the prediction of a recently proposed cavitation model (Sun, et al. (1) ). Among the findings are: (a) When cavitation did not occur, the measured pressure traces agreed well with the theory of non-cavitated oil squeeze film. In particular, tensile stresses of significant magnitudes were measured in the oil film. (b) When cavitation occurred, the measured pressure traces agreed well with the prediction of the new cavitation model. In particular, tensile stresses were measured in the oil film just before the arrival of the expanding cavitation front. (c) The measured cavitation duration correlated well with the new cavitation model. But the measured growth of the cavitation region was faster, and its maximum size was larger, than the model prediction. An analysis of the size effect of the cavitation nuclei, which were likely the entrained air bubbles, provided plausible explanations for the non-occurrence or occurrence of cavitation, as well as for some of the discrepancies between the measured results and model predictions.