Effect of Sidewall Corner Modification on the Flow Pattern in the Forebay of a Side-Inlet Pumping Station

To mitigate the severe recirculation and sediment deposition induced by highly sediment-laden flow in the lateral-inflow forebay of the No. 3 Pumping Station in Hong sipu, Ningxia, within the Yellow River Basin, this study investigates the effects of different corner configurations of the left and right sidewalls on the hydraulic characteristics of the forebay flow. A three-dimensional numerical model was established using ANSYS Fluent, with the Realizable κ−ε turbulence model and the Mixture multiphase model for water–sediment two-phase flow. The numerical model was validated against field measurements, and the variations in the flow-field structure and flow velocity in the lateral-inflow forebay with different sidewall contraction angles were obtained. The results indicate that after the flow enters the forebay from the channel, it rapidly changes direction under the influence of suction from the pump units, resulting in clearly differentiated flow regions within the lateral-inflow forebay. A high-velocity flow region forms in the central part of the forebay, while two irregular vortices of different sizes develop on both sides. As the angle α at the left sidewall corner gradually decreases, both the area of the recirculation zone and the vortex scale are significantly reduced. When the sidewall contraction angle α is 0.12 °, the reverse-flow area in the forebay decreases by 36.04%, while the sediment accumulation area decreases by 17.81%, effectively alleviating sedimentation in the forebay of water-diversion pumping stations located on sediment-laden rivers. Furthermore, under the α = 0.12° condition, which exhibited the best hydrodynamic performance among the investigated cases, variations in the angle β of the right sidewall within the range of 50–84° produce no significant changes. The findings can provide guidance and reference for the design, renovation, and upgrading of similar pumping stations.