Hydraulic performance improvement of a two-way pumping station through bell mouth shape design

A two-way pumping station is a specialized device that facilitates bidirectional water pumping and drainage. The pressure pulsation characteristics of two-way pumping stations have emerged as a prominent research focus in the field of hydraulic engineering. In this work, with the aim of systematically proposing optimization measures to ensure operational stability, a transient numerical simulation is conducted to elucidate the influence mechanism of the suspension height of the bell mouth (SHb) on the internal flow field and pressure pulsation of a two-way pumping station. High-precision experiments are performed to compare time-frequency domain characteristics under different SHb using a continuous wavelet transform (CWT). The findings indicate that an appropriate reduction in SHb effectively reduces unstable flow and pressure pulsation within the inlet conduit, consequently reducing the pressure pulsation of the impeller. With a reduction in SHb, the influx of low-velocity backflow into the bell mouth is prevented and the generation and propagation of suction vortices are suppressed. However, the reduction amplifies the flow impact between the mainstream flow and the bell mouth wall. The spatial distribution of the pressure pulsation is also examined, and it is found that a reduction in SHb increases the pressure pulsation intensity on the side facing the incoming flow and on the rear side, while the mainstream area tends to exhibit stability. In terms of time-frequency domain characteristics, a reasonable reduction in SHb leads to improved circumferential uniformity of the impeller inflow and the effective suppression of low-frequency disturbances.