Investigation on the Rotordynamics of a Rotor System With Air Film Damper (AFD)

Abstract

The flexible rotor systems are widely applied in the modern aero-engines which causes large radial displacement when passing through the bending mode. The vibration will develop after a long time working which may cause the rubbing between the stator and the rotor. Therefore, more effective damping should be introduced into the rotor system in order to control the vibration of the rotor system. In this paper, a novel air film damper (AFD) with metal rubber (MR) as an elastic outer ring is put forward as a supporting and damping component for rotor systems, which can not only provide effective additional stiffness and damping for rotor systems generated by the air film and metal rubber, but also adjust the clearance between the stator and rotor automatically due to the motion of MR in order to avoid the rubbing effectively. The mechanical model that explains the mechanism of AFD is established by describing the fluid structure interactions based on the motion of the components in AFD in a steady-state. The motion equation of the rotor system with AFD is constructed and the rotordynamic coefficients of the rotor system were obtained. The effects of AFD on the rotordynamic were analyzed. A test rig was constructed to verify the mechanism of AFD and the effects on the rotordynamics of the rotor system. The theoretical and experimental results identify that AFD can provide effective damping and additional stiffness for the rotor system and improve the rotordynamics of a rotor system significantly.