A Modal Transient Simulation Model for Flexible Asymmetric Rotors

Abstract

A simulation model is developed which accounts for an orthotropic as opposed to an axisymmetric rotor, i.e., rotors are considered whose stiffness and inertial properties in two mutually orthogonal planes are different. A rotor-fixed formulation is employed to define the rotor’s elastic deflections. Favorable characteristics of this formulation are that (a) the rotor’s inertial and stiffness properties are constant, and (b) the modal coordinates are nonoscillatory during synchronous motion. The validity of the formulation is verified by conducting transient simulations for a rotor having the approximate physical dimensions of a two-pole 500 MW alternator. The simulation model correctly simulates the rotor’s theoretically predicted dynamic behavior.