Dynamics of Vertical Magnetic Suspension Rotor and Touchdown Bearing: Touchdown Mechanism

During touchdowns of active magnetic bearings (AMB), rotor will generate different trajectory on touchdown bearings (TDB). The full rub will cause violent collisions and damages to both parts. By modeling radial and axial contact between rotor and TDBs, the dynamic and thermodynamic touchdown model of a vertical rotor with internal TDBs were established. Numerical simulation showed that the orbit response of vertical rotor after touchdowns was forward whirl, which is divided into two states: dry-friction whirl and dry-friction whip. There’s a limit speed associated with the natural frequency that enables the rotor to convert from synchronous positive precession to sub-synchronous positive precession. The contact force and temperature of inner race has increased significantly when rotor entering the sub-synchronous forward precession.