Energy loss and pressure fluctuation characteristics of coastal two-way channel pumping stations under the ultra-low head condition

The ultra-low head condition is a unique condition of the coastal two-way channel pumping stations, but the quantitative research on its hydraulic characteristics still needs to be improved. The entropy production method with computational fluid dynamics and the high-frequency pressure fluctuation test were employed to analyze the pumping device's internal energy loss and pressure fluctuation. The results show that the primary source of energy loss of the two-way channel pumping device under the ultra-low head condition is the turbulent dissipation caused by the velocity fluctuation of the impeller and guide vane, in which there are large irregular high entropy production areas on the pressure surface of the impeller and in the impeller channel. The high-frequency pressure fluctuation in the pumping device is mainly concentrated near the impeller, and the amplitude under the ultra-low head is 3.5 times the amplitude under the design head. Due to the dynamic and static interaction between the impeller and the guide vane, the frequency domain components of the pressure fluctuation at the outlet channel bell mouth are complex. Under the ultra-low head condition, the pressure fluctuation degree is intensified, the energy loss of each part is greater, and the low-frequency resonance should be prevented.