Abstract: By using a large-scale 1∶30 model of multi-level intake of hydropower station, we carried out experiment to research the minimum submergence depth for each stoplog. It was found that the connection beam on water surface could obviously eliminate the vortex at the inlet. The flow pattern at the inlet could meet the requirement when the operating water level of each stoplog gate is above the bottom of its corresponding connection beam. The closer the connection beam to the water surface, the better the vortex elimination effect is; while the distance of the beam from the water surface increases, the inlet flow pattern is mainly affected by submergence. Inlet configuration is the basic factor which determines the flow pattern, and the proper configuration of connection beam plays a key role in eliminating vortex. The research findings provide guidance for the arrangement of connection beam at the intake of power station, and serve as a reference for other buildings to eliminate vortex.

Key words: multi-level intake, stoplog gate, connection beam, minimum submergence depth, flow pattern at the inlet