Abstract: Physical model tests were conducted to solve the technical problems of an open channel closure for a hydropower project with large water depth, high water velocity, high drop, high unit-wide power and qualified closure materials which are difficult to be obtained. Tests with different dikes and closure gaps were carried out and a proper location of dike axis was determined. Results show that the recommended closure layout increases the flow path, reduces the hydraulic gradient at the closure gap, and results in S-shaped flow pattern. Moreover, the S-shaped closure layout bends the flow path, and enhances the flow turbulence, increases flow resistance and kinetic energy dissipation, thereby improving the flow pattern at the closure gap and reducing the hydraulic difficulty. This research provides useful data for the closure construction and can be a reference for similar projects.

Key words: open channel closure, optimization of closure scheme, diverting wall, experimental investigation