Dynamic Response of Rubbing Happening In A Flexible Rotor-Bearing System

Abstract

To reduce the steam loss and raise the efficiency of the steam turbine, the vapour seals are applied in the inner cylinder of the steam turbine. The small gap may easily results in the rubbing happening in the inner cylinder. Sometimes, the rotor is a flexible rotor. In this paper, dynamic response of rubbing happening in a flexible rotor-bearing system was studied. A simplified flexible rotor-bearing system was constructed, whose rotating speed was between the 1st and 2nd critical rotating speed. Thermal effect was considered in the analysis, i.e. the rubbing introduce heat and result in the thermally induced vibration. The transient thermal bow was treated as a pair of moments functioning on the shaft segment where rubbing happened. Simulation shows the amplitude and phase of vibration would be stable after a long time. The severity of rubbing affect the stabilization time, which could be regarded as a diagnostic feature to identify the severity of rub happening in a flexible rotor-bearing system. Keywords-thermally induced vibration; equivalent thermal moment; stabilization time; rubbing; flexible rotor-bearing system