Analysis of Coupled Vibration Response in a Rotating Flexible Shaft-Impeller System

Abstract

This paper presents a way of analyzing the vibration of a rotor shaft system coupled with flexible impellers based on the transfer method. Each of the flexible impellers is modelled so that it comprises an inertia and an elastic hinge based on the assumption that any impeller’s vibration mode except its one-nodal diameter has no dynamical connection with a shaft. The stiffness of the hinge is based on the eigen frequency of its mode calculated by means of a finite element method, or obtained by experiment. The method developed allows the calculation of the vibration response of a rotor shaft system consisting of several flexible impellers and several bearings when it is subject to an out-of-balance force. Theoretical results are compared with experimental data and show very satisfactory agreement. This simple method appears therefore to be practical and efficient to predict the dynamical characteristics of a high speed rotor system with coupling of impeller flexibility.