Shape optimization of the spillway approach channel of Baleh Hydropower Project based on numerical simulation

Abstract Baleh Hydropower Project has a protruding headland between the spillway inlet and the power intake structure. Based on the results of the model tests, the velocity gradient near the protruding headland under high flow conditions is large and an unstable vortex occurs. To address the unfavorable flow problems of the original spillway approach channel, this paper simulates the original spillway approach channel using a three-dimensional turbulence numerical model and verifies it with the model tests, and provides numerical simulation results for two optimized cases: excavation and backfilling. The calculation results show that both backfilling and excavation optimization cases improve the right side flow pattern, the unstable vortex disappears, and the flow between the approach channel and the spillway inlet is smoother than the original design. Comparing the two optimized cases, the average flow velocity in the upstream section of the approach channel of the excavation case is reduced, but the flow velocity near the right bank of the approach channel close to the spillway gate bay inlet becomes larger, and the average flow velocity of the excavation modified case is more unevenly distributed.