Hydraulics Mechanism and Application of a Swirling Device in Morning Glory Shaft Spillway

摘要

According to swirling flow mechanism, a novel shaft spillway which consists of submersible and spiralflow-generated piers and flaring weir was developed. It has shown that the stable and swirling flow with air core in the vertical shaft was generated under a variety of weir water head, thus the negative pressure was eliminated and also the cavitation was prevented. Besides, the energy dissipation ratio of the shaft spillway was increased significantly. The flow mechanism of this novel piers is: when the water head above the weir is low, the water will flow to the vertical shaft along the piers wall, and the stable and swirling flow with air core is generated, when the depth of water been significantly raised over the top, the inflow angle will be automatically adjust under the inertial forces which leading to the larger discharge capacity, and meanwhile, the water will be synchronously swirling under the drag force of bottom flow. The design theory and the research results have been firstly applied in the shaft spillway of Qingyuan pumped storage power station in Guangdong province.