Compare the hydraulic characteristics of triangular weir fishways with different triangular notch angles

In order to explore the advantages of the triangular weir fishway and the influence of the angle of the triangular weir fishway on fish migration, this paper simulates the internal flow field and free surface of the fishway by using large eddy simulation (LES) and volume of fluid (VOF) method, respectively, and analyzes the hydraulic characteristics of the triangular weir at the three angles, where for the analysis of turbulent structure, omega (Ω) eddy identification is also used. And based on the analysis results, the length of the pool chamber and the height of obstacles were changed to obtain a more stable flow regime. The results show that the main flow is obvious, the turbulent kinetic energy distribution is regular and small in value, and the angle has an effect on the return flow. The vortex structure mainly existed in the mainstream area with high flow velocity, the air-liquid interface and the porosity, and was distributed transversely. 90° triangular weir had the largest vortex structure, and 105° triangular weir had the smallest. 75° triangular weir fishway could effectively attenuate the energy of the main stream, and the area of high velocity flow was small, which made the migratory conditions more favorable. Adding obstructions to the mainstem area can reduce flow velocity and turbulent kinetic energy. The triangular weir structure can improve the flow structure of the fishway, and the different angles and water depths provide a variety of flow conditions for a variety of fish migrations, providing new ideas for the fishway.