Study of energy dissipation mechanisms and pressure pulsation spectrums in a vertical axial flow pumping station on the ultra-low head condition based on multiple analysis methods

Abstract

In the context of global energy shortages, the efficient and safe operation of pumping stations is essential for improving energy utilization and achieving energy conservation and emission reduction goals. Vertical axial flow pumping stations, especially those operating under ultra-low head conditions, face specific challenges related to energy dissipation and pressure pulsations — both critical to enhancing overall efficiency. This study employed an entropy production head loss model and pressure pulsation test to assess the energy dissipation and pressure pulsation characteristics of the pump system. Results showed that the total head loss under ultra-low head condition (0.18 $H_d$) is 1.26 times higher than under design condition ($H_d$). The misalignment between the outlet velocity angle of impeller and the inlet vane angle of guide-vane was identified as the primary factor contributing to energy loss and hydraulic instability. Additionally, wall effects caused significant head loss near the blade and shroud regions. Under non-design conditions, pressure pulsations in the impeller and guide-vane regions fluctuated significantly. To analyze these fluctuations, feature mode decomposition (FMD) and energy flow density (EFD) methods were applied, demonstrating a strong correlation between EFD and peak-to-peak value (PPV). These findings offer important insights for optimizing pump station design and improving operational efficiency.