Evaluation of flip bucket-plunge pool energy dissipator
[Thesis]
T. Zahoor
Colorado State University
1992
298
Ph.D.
Colorado State University
1992
A hydraulic model was built to understand the process of energy dissipation within a flip bucket plunge pool basin and to examine the flow characteristics. The model was investigated for eight flip bucket angles varying from 0 degree to 60 degree, two basin layouts, each examined for four discharges, and seven tailwater conditions. The pressure distribution in the bucket and drawdown water depth in the plunge pool basin were compared by analytical equations developed on the principles of energy and momentum. In general, the observed data followed the analytical equations, but correction coefficients were required. A Froude number for curvilinear flow is described and it is used to correlate the energy dissipation in the bucket. The flow characteristics in the flip bucket and plunge pool basin are described. The flow conditions in the basin depended primarily upon the position of the jet impingement in the basin and the ability of the jet to penetrate down into the water cushion. The performance criteria have been developed from the jet impingement in the basin water cushion and the resulting drawdown in the basin. Two limits were established for a satisfactory basin, and the associated flow parameters are described empirically. The criteria are presented in graphical form with the help of two design curves, an upper performance curve, PC, and a lower performance curve, PC2. A basin designed between the upper and lower curves will perform satisfactorily and will experience the acceptable flow conditions and energy dissipation. Design guidelines are suggested for the selection of basin depth and basin configurations. The zone between the two curves is suggested for a basin protected on the sides and bottom. However, for an unprotected basin, the area below the curves is recommended. A similar basin configuration as recommended by the US Bureau of Reclamation criteria is proposed except the basin should be positioned around the jet impact area. An impact point at one third of the floor length from the upstream slope is suggested. The criteria were used to evaluate the plunge pool basins at Tarbela Dam, Pakistan; Jiguey Dam, Dominican Republic; and the Cabora-Bassa Dam in Mozambique.