磁轴承激励下转子系统动力学特性

To analyze the vibration mechanism of the rotor systems excited by magnetic bearings, a calculation model for dynamics characteristics of a double-disk rotor system was established by using one-dimensional finite element method. The dynamics behaviors of rotor system under different types of magnetic bearing excitations were studied. Results show that the co-rotating sweep frequency exciting forces excite forward whirl mode of the rotor systems, while the counter-rotating sweep frequency exciting forces excite backward whirl mode. In both cases, the rotor system whirls in a circular trajectory. The unidirectional harmonic exciting force may be decomposed into the sum of co-rotating and counter-rotating exciting forces, therefore both of the backward whirl and forward whirl modes of the rotor system are excited and the rotor system whirls with an elliptical trajectory under the effect of unidirectional harmonic sweep exciting force. Under bi-directional harmonic sweep exciting forces, the whirl direction and whirl trajectory of the rotor system depend on the phase difference of the two exciting forces. Research results provide a theoretical basis for the selection of excitation scheme of magnetic bearings when evaluating the stability of rotor systems of high-pressure compressor.