Controllable magnetically sensitive rotor support element for reducing oscillation and force transmission

The hydrodynamic bearings are used to support rotors for their high loading capacity, simple design, and quiet operation. To increase stability limit of lateral vibration of rotating machines, the hydrodynamic bearings are combined with classical squeeze film dampers. This technological solution is widely used to support rotors of high speed turbomachinery. The amount of damping in the rotor supports influences suppression of the vibration amplitude and magnitude of the force transmitted between the rotor and its stationary part. A simple dynamical analysis shows that to achieve optimum performance of the damping elements of rotors working in a wide range of operating speeds, their damping effect must be adaptable to the current angular velocity. This is possible if the classical squeeze film dampers are replaced with controllable damping devices. The presented article deals with a proposal and investigation of a new type of such support element that is a combination of a hydrodynamic bearing and of a magnetorheological squeeze film damper and with its application for rigid rotors. The computational simulations show that higher damping is needed for lower rotor velocities and lower one for higher speeds to achieve optimum compromise between the vibration attenuation and minimization of the force transmitted between the rotor and the stationary part. The results also show that damping in the rotor supports has almost no influence on the rotor oscillation amplitude for higher angular velocity. The proposal of the novel controllable rotor support element, the development of its mathematical model, and learning more on its effect on vibration attenuation and on the force transmission are the principal contributions of the research work carried out.