Influences of thrust magnetic bearing and journal tilt on dynamic characteristics of rotor system

摘要

The influences of thrust magnetic bearing and journal tilt on dynamic characteristics of rotor system are studied mainly in this paper. The outcome shows: the coupling effect of thrust magnetic bearing has principally influence on low-frequency taper vortex, the damping inherent frequency of relevant eigenvalue is increased along with the decrease of dimensionless damping, the system stability of relevant vibration mode reduces. The influences of coupling effects of thrust magnetic bearing and tilt of journal on critical rotational speeds of system are very large, and the stability of system reduces greatly. Under some set of control parameters near the border in stable region, in the ideal condition of rotor in exact alignment of magnetic bearings, the system is stable when the coupling effect of thrust magnetic bearing is neglected in the calculating model, and the system is instable when the coupling effect of thrust magnetic bearing is considered in the model. In the general condition of rotor tilting in the magnetic bearings, the system is sable when the coupling effects of thrust magnetic bearing and radial magnetic bearings due to rotor tilting are neglected in the calculating model, and the system is instable when the coupling effects is considered in the model. The stable system in the ideal condition of rotor in exact alignment of magnetic bearings may become instable in the general condition when the rotor tilts in the magnetic bearings. That shows it is important that the influence of coupling effects of thrust and radial magnetic bearings due to the rotor tilting must be considered in the study of rotor-magnetic bearings system dynamic characteristics, and also shows it is important that the rotor is mounted and debugged in ideal alignment of magnetic bearings.