A model of a high-head bottom spillway with interaction of concentric swirled flows: Fid-Bau Portal

A model of a high-head bottom spillway with interaction of concentric swirled flows

Zuikov, A. L. / Chepaikin, G. A.

Conclusions Eddy spillways compared with, traditional schemes have a number of advantages: possibility of re-equipping temporary diversion spillways into service spillways and eliminating the construction of multilevel systems, which can effect a considerable reduction of the volumes of works and capital investments on spillways of high-head hydro developments. The need to construct large energy-dissipating structures at the tunnel outlet — stilling basins, walls, dissipators, ski-jumps, etc. — is eliminated. An improvement of the cavitation conditions in the waterway as a consequence of reducing the flow velocity can effect in some cases a saving due to a reduction of the requirements imposed on the quality of making the linings and in others can eliminate the danger of erosion of the linings and thereby reduce operating expenses.The investigated spillway is intended for using conventional service vertical-lift and radial gates operating in normal free-flow regimes with a high capacity and possibility of passing trash. Its construction does not cause technological difficulties.The investigated spillway system based on the effect of the interaction of concentric, oppositely swirled flows satisfies the requirements of passage and regulation of the discharge and necessary dissipation of the excess kinetic energy of the flow at a low level of fluctuation loads on the conduit walls.Dissipation of the bulk of the excess energy is accomplished on a short section with a length of 1.5–2 diameters of the exit conduit, which permits making it short. This leads to convenient layouts under mountain conditions and In the case of small spillway lengths, for example, in the lower parts of gravity and arch dams.The layout of the investigated spillway system can be different depending on the local conditions, restrictions are not imposed on it with respect to the design and route of the entrance and exit conduits and location of the intakes, gate chambers, hydromechanical equipment, and transition of the swirled flows. The exit conduit can be made both in pressure and free-flow variants. This permits wide variation during designing.