Study on Cavitation Characteristics of Radial Gate with Sudden Lateral Enlargement and Vertical Drop in Open Channel Flows

The service gates of high-head water release structures are mostly radial gates with sudden lateral enlargement and vertical drop. As the control transition section from pressurized flow to open-channel flow, this flow passage not only meets the layout requirements for gate sealing, but also possesses the function of aerating high-velocity flow to protect the baseplate and side walls of the open-channel section. However, as application conditions become increasingly complex, several projects have experienced cavitation erosion damage on the side walls after prolonged operation under high water levels and partial-opening conditions. To address this problem, this study takes the sediment discharge tunnel of a hydroproject as the research object, using a combination of physical model tests and numerical simulation. The hydraulic and cavitation characteristics of the open-channel section under various gate openings are analyzed, and the cavitation mechanism on the side walls is revealed. The shape of the sudden lateral enlargement and vertical drop is proposed according to the requirements of the gate sealing arrangement. Meanwhile, for existing and planned similar projects with partial opening operation requirements, recommendations for cavitation-reduction measures and operational methods are also presented, with the aim of providing reference for similar projects.