Numerical Analysis of the Dead-Band Clearance Effect on the Vibrations of a Vertical Rotor
The present work tackles the dead band clearance problem of rotors guided by ball or roller bearings. There are situations when the rotor can be only temporary in contact with the casing. The closed-loose nature of the rotor-stator contact leads to a non-linear rotordynamic response. A test rig dedicated to the experimental analysis of this problem was presented in a previous paper . The test rig is based on a vertical rotor guided by ball bearings and lifted by an aerostatic thrust bearing. The ball bearings are mounted with three different radial clearances: “small”, “medium” and “large”. The results for the low and mild radial clearances showed a linear behavior of the rotor characterized by synchronous responses with forward or backward whirls. A non-linear signature of the rotor was obtained for the large radial clearance with sub-synchronous bifurcations and internal resonances. The present paper presents the numerical analysis of the same rotor and is intended to reproduce the experimental results. The rotor was modeled with Timoshenko beam elements. Full non-linear calculations were performed by simulating a constant acceleration of the rotor from zero to 400 Hz in 50 s. Calculations showed that the value of the dead-band clearance is a capital parameter for triggering non-linear responses of the rotor.
KeywordsRotordynamics Dead-band clearance problem
The authors are grateful to Centre National d’Etudes Spatiales and to Airbus Safran Launchers for supporting this work.
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