Effects of vertical deflectors on rooster tail geometry

Behind piers across spillway, super critical flow generates standing waves known as rooster tails. One of the most important parameter which has to be evaluated is the height of rooster tail. In fact, high rooster tails, especially occurring close to the side walls, increases the construction cost, as countermeasures to contain them have to be adopted. In this study, the scale model of the El Chaparral dam, with a downstream chute expansion of 50° slope, has been used and the maximum flood was simulated. Experiments have been done with different angles of vertical deflectors for different Froude numbers. The aim of the paper was to optimize the angle of vertical deflectors to minimize rooster tail height.