Dynamic Characteristics of a High-Speed Rotor With Radial and Axial Foil-Bearing Supports

Abstract

An asymmetric rotor (19N; 4.3 lb), supported radially and axially by compliant bearings (foil bearings), is subjected to severe excitation by rotating unbalance (43 μm.N; 6100 μin.oz) in the “pitching” mode, at speeds to 50,000 rpm. The resilient, air-lubricated bearings provide very effective damping, so that regions of resonance and instability can be traversed with impunity, with amplitudes and limit-trajectories remaining within acceptable bounds. A novel journal bearing is introduced, in which a resilient support is furnished by the outer turn of the coiled foil-element, initially bent to form an open polygon. The experimental apparatus and procedure are described, and the response of the rotor and flexible support system are copiously documented by oscilloscope records of motion.