Modelling and experimental study of the transient response of an active magnetic bearing rotor during rotor drop on back-up bearings

Abstract

The back-up bearing is a key safety component of active magnetic bearing (AMB) machinery. For many unexpected reasons, the rotor operating at full speed may drop onto the back-up bearings. Sometimes, full-clearance whirling motion is induced, which is particularly harmful to the machine. Thus, it is of great importance to understand the transient behaviour of the back-up bearing as well as the AMB rotor. In this paper the transient response of the AMB rotor during rotor drop is studied numerically and experimentally. Firstly, a modelling method is introduced. Then, an experimental set-up is built, and varied AMB rotor drop tests with different back-up support conditions are performed. Factors leading to full-clearance backward whirling motion are studied. The experimental results are compared with simulation results. Finally, conclusions based on both simulation and experiment are given.

Keywords

active magnetic bearings back-up bearings contact modes rotor drop

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