An active hydrodynamic bearing for controlling self-excited vibrations: theory and simulation

Fluid-film bearings can suffer from flow-induced instabilities known as ‘whirl’ and ‘whip,’ especially when supporting lightly-loaded shafts. This phenomenon can lead to large rotor (self-excited) vibrations, which eventually result in rotor-bearing failure. In this paper, we introduce a new active hydrodynamic bearing to mitigate such vibrations in lightly loaded rotating machines. The system contains a rotating bushing, actuated by a motor, that serves as the control input. This input is used to control the mean flow velocity in the bearing and thereby the journal vibration. A simple feedback control law is proposed for the bushing velocity, and numerical simulations are presented to evaluate the active bearing.