Impact of inlet flow velocity on sediment reduction in pump station forebays

Pump stations are critical for effective water management in China, particularly in sediment-laden regions such as Ningxia, where vortex flow patterns in forebays result in sediment deposition and diminished operational efficiency. Through this research endeavor, numerical simulations and engineering measurements were employed to systematically analyze the causes of adverse flow patterns induced by the water-sediment two-phase flow in a sudden expansion pump station located in Ningxia, focusing on seven cases that examined vortex behavior and sediment concentration. Results indicate that in a forward forebay, the inflow velocity at the diversion channel entrance is correlated with suspended sediment concentration. Compared to other cases, case 5 produces a smaller vortex that has a minimal impact on the flow pattern and exhibits the lowest sediment concentration. Applying the Q-criterion reveals that case 5 possesses the smallest vortex structure volume. Additionally, a quadratic polynomial relationship between inlet velocity and sediment deposition efficiency was established, further confirming the accuracy of case 5. At an inlet velocity of 1.065 m/s, sediment deposition was markedly reduced as the vortex strength decreased, enabling sediment particles to escape, thereby enhancing the operational efficiency of the pump station. This study offers optimized operational conditions and theoretical guidance for the management of pump stations in high-sediment regions.