Simulation of the Effect of Flip Bucket Edge Angle on Flow Hydraulic Characteristics

The Flip bucket is one of the spillway components of dams used to dissipate the flow kinetic energy. In these dissipaters, Part of supercritical flow energy due to air friction and partly due to mixing and turbulence in the erosion cavity that is formed at the landing site is dissipated. One of the geometrical parameters affecting the hydraulic performance of flip buckets is the angle of the bucket edge. In this study, using FLOW 3D software and RNG K-ε turbulence model, flow on Gavoshan Dam spillway and flip bucket was simulated in order to determine the hydraulic flow characteristics and the effect of bucket edge angle on the hydraulic flow pressure, outlet depth, velocity and developing of outlet jet as well. In order to validate the parameters obtained from numerical analysis, the experimental results of Gavoshan dam spillway hydraulic model have been used. Comparison of the results of numerical model with experimental data indicates acceptable agreement of the numerical results. The results show that increasing the angle of the bucket edge has a little effect on the maximum pressure on the bucket while it increases the depth and decreases the outlet flow velocity of the bucket. The 30° angle was determined as the optimum angle of the flip bucket edge in terms of increasing energy dissipation rate. Also for a fixed flip bucket edge angle with increasing discharge, the horizontal length of the upper and lower nappes of the jet are increased.