Non-synchronous vibration of rotor blade in a six-stage transonic compressor

Abstract

This paper presents an experimental study on the Non-Synchronous Vibration (NSV) in a six-stage transonic compressor. The first part of the paper describes the NSV phenomenon of Rotor 1, which occurs when both Stator 1(S1) and Stator 2(S2) or S1 only are closed. Detailed measurements and analysis are carried out for the former case through the unsteady wall pressure and the Blade Strain (BS). The spinning mode theory used in the rotor/stator interaction noise is employed to explain the relation between the circumferential wave number of the aerodynamic disturbance and the Nodal Diameter (ND) of the blade vibration. The variations of the vibration amplitudes of different blades and the Inter-Blade Phase Angles (IBPAs) at different moments suggest that the evolution of NSV is a highly nonuniform phenomenon along the circumferential direction. In addition, the difference between the wall-pressure spectra generated by the NSV and the classic flutter has been discussed. In the second part, the variations of aerodynamic loading due to the adjustment of the staggers of the Inlet Guide Vane (IGV), S1 and S2 have been investigated. It is found that closing S1 only can result in a great fluctuation to the performance of the front stages, which might be detrimental to the flow organization and increase the risk of NSV. In contrast, the effect of closing S2 only on the performance of the first two stages appears to be slighter relatively.