The Analytical Solution and The Existence Condition of Dry Friction Backward Whirl in Rotor-to-Stator Contact Systems

Dry friction backward whirl is a self-excited vibration state in rotor-to-stator contact systems, by which the rotor is in continuous contact with the stator, slipping continuously on the contact surface and whirling backward at a supersynchronous frequency. To correctly cope the response of dry friction backward whirl, the effect of dry friction must be taken into account in rotor/stator models. From the knowledge on the characteristics of dry friction backward whirl, the whirl frequency, the existence condition and the solution of this response are derived analytically in this paper. The analytical results are verified by simulations and shown in good correspondence to the experimental observations.