An Experimental and Theoretical Study of Cavitation in a Finite Submerged Squeeze Film Damper

In fluid film lubrication, pressure often seeks a level lower than the lubricant vapor pressure, in which case the liquid film ruptures and a vapor cavity is formed. The Jakobsson-Floberg-Olsson (JFO) model would seem to correctly predict the extent of the cavitation region in heavily loaded finite bearings and to specify proper pressure boundary conditions on the interface. However, this model is difficult to apply in practice, requiring extreme numerical effort in guessing the unknown cavity shape and checking flow balancing. In the present study, we propose a simplified model which agrees well with the JFO conditions, and provide supporting experiments. The ordinary differential equations for the distance of cavity boundary from the bearing centerline and the pressure profile at the bearing centerline are obtained by using the integral method. Compared to results obtained by the modified Elrod algorithm, considerable numerical work is saved and little accuracy is lost. Experiments are conducted with a submerged circular-centered orbit squeeze film damper bearing with both ends open. In the cavity the pressure is nearly constant and almost equal to the absolute zero pressure. Compared to the results predicted by the present model, agreement with experimental measurements of the centerline pressure profile, the size, and location of cavity is very good.