Numerical study on the dynamic evolution of cavitation and pressure fluctuation in a centrifugal pump during the startup period

Abstract

This paper investigates the evolution of cavitation and pressure fluctuation characteristics in a centrifugal pump during the startup period. The finite volume method is adopted to simulate the dynamic process. In order to characterize the acceleration characteristics, the rotation speed and flow rate are not constant, but vary with time. First, steady numerical simulation is performed on the external characteristics to verify the accuracy of the numerical procedure. Subsequently, the cavity evolution process and pressure fluctuation varying with time are analyzed in detail. Specifically, the short-time Fourier transform (STFT) method is employed in the post-process considering its advantage for non-stationary signal treatment. The results indicate that both the frequency and amplitude of pressure fluctuation increase with impeller speedup. Also, transient operation makes the average pressure at the inlet of the impeller decrease to evaporation pressure, leading to an increase in vapor volume fraction. Moreover, both impeller-tongue interaction and impeller-diffuser interaction influence the fluctuation of cavitation.