Dynamics of turbine rotor's rub-impact with model accounting for Alford forces

摘要

Dynamics of rotor-to-stator rub-impact has been widely discussed with simplified models, namely pure structural model of a Jeffcott rotor under imbalance. However, study on this problem with comprehensive models that represent better the actual operation conditions than the simplified models has hardly been seen in literatures. This paper initiates an investigation on this subject. Three component models, including an Alford force model, a rub-impact force model and an imbalance force model, are presented. A global rotordynamic model, which incorporates the Alford forces into the restoring force and considers the imbalance forces and rub-impact forces as excitations, is developed with a multi-turbine-rotor system as physical prototype. The global model is solved with the fourth-order Runge-Kutta method. The dynamic properties represented by the solved response are demonstrated by means of bifurcation diagrams, waveforms, frequency spectrums, orbits, and Poincare maps. Conclusions are summarized in the end. It is believed that the conclusions should make sense to the dynamical design and fault diagnosis of turbomachinery.