Dynamic mode decomposition based investigation of unsteady flow characteristics and pressure pulsations in centrifugal pumps operating under partial load conditions for scientific advancement

Abstract

To analyze the unsteady flow properties and their effect on the centrifugal pump performance, we employ a hybrid approach using numerical and experimental methods to evaluate and identify complex flow states. The pressure variations measured experimentally at the centrifugal pump's input and outlet are analyzed utilizing the continuous wavelet transform (CWT). The flow field data generated by numerical simulation is studied to analyze the distribution of pressure, turbulent kinetic energy and distribution of the velocity streamlines under different working conditions, the method of Dynamic Mode Decomposition (DMD) is utilized to examine distribution of vorticity within a centrifugal pump working under conditions of partial load and designed flow rate. The aim of this study was to investigate the link between the inlet and outlet pressure fluctuations of the pump and the flow instability. Using CWT analysis of the pump inlet and outlet pressure pulsation signal, the amplitude of the rotor frequency (f₀) and twice the rotor frequency (2f₀) increased significantly when the flow decreased. The decrease of flow rate promotes the scale and number of vortices, and also promotes the development of pump vibration strength. With the decrease of the flow rate, the vortex constantly diffuses from the suction side of the blade to the pressure side, the pressure at the impeller shows obvious heterogeneity, and the strength of the vortex structure also increases and gradually diffused, resulting in the obstruction of the flow channel. These findings provide a scientific basis for ensuring the stable operation of the centrifugal pump.