A 2D Mathematical Model of a Short Magnetorheological Squeeze Film Damper Based on Representing the Lubricating Oil by Bilinear Theoretical Material

Abstract

Unbalance is the principal source of excitation of lateral vibrations of rotors and of increase of the time varying forces transmitted to the rotor casing. These undesirable effects can be reduced if the damping devices are inserted between the rotating and stationary parts. To achieve their optimum performance in a wide range of rotational speeds their damping force must be adaptable to the current operating conditions. This is offered by application of magnetorheological damping elements. To learn more on their properties a new 2D mathematical model of a short magnetorheological squeeze film damper has been developed and is presented here. The model is based on representing the magnetorheological oil by bilinear material whose flow curve is continuous unlike to the models based on Bingham or Herschel-Bulkley theoretical fluids. This reduces the nonlinear character of the motion equations and increases computational stability of the procedures used for their solving which was confirmed by the performed computational simulations. In addition, behaviour of the developed model of the squeeze film damper was completed with the effect of the magnetic force acting between the dampers rings if the rotor journal takes an eccentric position. Application of the developed mathematical model made it possible to learn more on the vibration attenuation of rigid rotors supported by magnetorheological squeeze film dampers working in a wide range of operating speeds.