Abstract: Based on the turbulent bulk flow theory and perturbation analysis, a dynamic model of Jeffcott rotor-annular flow coupled system was developed. Taking a large-scale canned motor pump rotor system as an example, the effects of rotating speed, rotor eccentricity, and stator and rotor wall frictions on dynamics of the rotor-annular coupled system were investigated using the complex mode analytical method. The analytical results show the annular flow causes the decrease of natural frequency greatly and generates divergence and leap of mode, the rotor eccentricity induces instability of rotor and the decrease of instability speed, and the stator and rotor wall friction effects increase rotor instability speed significantly.

Key words: rotor, annular flow, dynamics, complex mode analysis