Resonance risk assessment method on a storage pump’s centrifugal impeller by considering the hydrodynamic damping ratio

Abstract

How to accurately predict the resonance operating point and the corresponding vibrating amplitude of the underwater structures are of interest in the field of hydraulic machinery. In the present investigation, a resonance risk assessment method consisting of unsteady CFD, modal work approach, and harmonic response analysis is established, and an implementation is carried out on a centrifugal impeller of a storage pump. The simulation results (head, efficiency, and pressure pulsation) are carefully verified by comparing them with the experimental results, with relative deviations within 11%. Regarding the prototype pump, the amplitude of the pressure pulsation coefficient is almost identical to the model pump, with a relative deviation of 13.5%. It is found that the hydrodynamic damping ratio is gradually decreased if the operating flow rate deviates from the design one, based on the modal work approach. And then, the harmonic response is carried out on the prototype impeller, by setting the pressure pulsation as the initial excitation condition and considering the hydrodynamic damping ratio. Finally, the natural frequency, the resonance amplitude, and maximum equivalent stress are quantitatively determined, which proves that the resonance risk assessment method has the potential to judge the resonance operating point and destructiveness in practical engineering.