Full rubs, bouncing and quasi chaotic orbits in rotating equipment

Abstract

In order to improve performance, closer tolerances are usually required in high performance turbomachinery. This often results in an increase in rotor casing/real rub sensitivities. The objective of this paper is to investigate the effects of mass, support stiffness and blade stiffness during a rotor-casing rub event. Special emphasis will be given to defining the tuning/detuning effects of the system during such variations in mass and stiffness. The overall model will incorporate the influence of : (i) casing and rotor inertia, (ii) casing and rotor support stiffness, (iii) contact friction induced during rub interaction, (iv) single and multiple blade contact, as well as (v) lateral and radial blade stiffness effects. The main thrust will be investigate the different regimes of rubbing, i.e. the development of full rubs, rigid bouncing and essentially chaotic behavior due to the changes in rotor-to-casing mass and stiffness ratios, as well as blade stiffness and friction effects. © 1990.