Characteristics of dry friction backward whirl—A self-excited oscillation in rotor-to-stator contact systems

In this paper, the response characteristics of dry friction backward whirl of a general rotor/stator model, which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces, are investigated. The existence boundaries and the whirl frequencies of the dry friction backward whirl are determined analytically. It is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions, either standing completely separately, or overlapping each other partly, or one containing the other completely, depending upon the system parameters. The whirl frequencies in the two existence regions are quite different and may jump between the lower and the higher values with the variation of the rotating speed. The results have been found to have good correspondence in the related rotor/stator rubbing experiments.