Analytic and Experimental Investigation of Rotordynamic Response and BackwardWhirl Induced by Split Resonance

摘要

Rotordynamic response phenomena, including backward whirl, were investigated bothanalytically and experimentally. A two degrees-of-freedom rotor model was developed to simulate the steady state, lateral vibration characteristics of a simply supported, single disk rotor. This model includes the effects of direct and cross-coupled, linear damping and stiffness coefficients. The computer model was used to quantify the influence of bearing characteristics on rotordynamic response. The presence of split resonance, which appears to be due to separate and distinct natural frequencies in the two orthogonal lateral directions and the occurrence of backward whirl between these two frequencies was studied. The effects of geometric imperfections in the bearing sleeve, gravitational forces and bearing support stiffnesses were isolated using the experimental apparatus. It was determined that the split resonance induced backward whirl and the different natural frequencies were caused by asymmetric stiffness of the bearing support structure as well as gravitational forces. Bearing imperfections did not create the backward whirl phenomena. The bearing support characteristics necessary to create the observed rotor orbits were determined.