Critical Speed Problems Encountered in the Design of High-Speed Turbomachinery

This paper discusses critical speed problems encountered in the operation and design of high speed turbomachinery. Plots are given showing how the first and second critical speeds are a function of the bearing spring rates and methods for controlling these spring rates are given. Synchronous and nonsynchronous whirls are discussed. The effect of non-linearity of the bearings and damping due to the bearing friction is included. Results of analysis of rotors on journal bearings, in which the bearing equations are solved simultaneously with the dynamics of the rotor, are given.