A study of the nonlinear interaction between an eccentric squeeze film damper and an unbalanced flexible rotor

In this paper, the nonlinear interaction between an eccentric squeeze film damper and an unbalanced flexible rotor is investigated, paying particular attention to the effect of cavitation in the damper. A harmonic balance method that uses the receptance functions of the rotating linear part of the system to determine periodic solutions to the nonlinear problem is used to predict vibration levels in a test rig. By comparing predictions obtained respectively with, and without, lower pressure limits for the squeeze film damper model, it is concluded that cavitation is promoted by increasing static eccentricity and/or unbalance level. This, in turn, is found to have a profound effect on the predictions for the critical vibration levels, which such dampers are designed to attenuate. Experimental results are presented to support the findings.