Abstract: The outlet structure of the hydropower station in this research consists of several spillway tunnels for joint flood discharge. It has a large discharge volume and high water head, with narrow river course at the outlet, and the downstream plunge pool is located at the turn of the river. Owing to this, the energy of the discharge is concentrated and the returning of the trajectory nappe is deviated. To address these two problems, we put forward the flip bucket layout suitable for the actual situation by means of large-scale hydraulic model test. By comparing different schemes and considering the overall joint discharge and energy dissipation, we proposed the optimal layout design. It could serve as a reference for similar projects.

Key words: hydraulic model test, spillway tunnel, energy dissipation and erosion control, joint discharge, flip bucket optimization