The experimental study of the effect of the geometry of the downstream flip bucket on the scouring of its tail water

Using flip buckets as a part of the flow dissipaters in vertical case in dams would lead to dissipation of the energy from the flood passage. This structure is used to reduce costs in comparison with other energy dissipaters. Water jet collision with the river bed leads to the creation of scouring hole which can reduce the stability of dams and relevant structures. In the present study, the scouring phenomenon of the downstream of a flip bucket in free conditions and also in the presence of slots with rectangular and triangular shapes in various intervals distances with 9 flow rates and a total of 45 tests have been investigated. The results of this study showed that the presence of a slot would have a lot of effects on the depth and extent of scouring, so that a flip bucket with alternate rectangular slot compared to a non-slotted case causes about 13 percent less scour. Also, the maximum scour depth in bucket mode with alternate rectangular slots occurred in a more favorable range than the rest of the models. Then, the obtained results were compared with a number of empirical formulas and it was determined that Martinez B relation provides closer results to real values.