Experimental Study of Parallel Jets Scouring, considering the effect of jets distance on erosion rate

The scouring process at downstream of the hydraulic structures is a complex phenomenon and many parameters affecting its amount. Failure to control this phenomenon causes damages to the dam and its associated hydraulic structures. In this research, the scouring caused by the combination of jets outlet from a gated spillway was investigated experimentally and the combination of jets adjacent to each other or with a distance from each other inside the plunge pool was studied. For this purpose, 25 experiments have been carried out on the experimental model and the effect of important parameters such as flow rate or discharge, densiometric Froud number, depth of tail water and how jets are combined.The results show that in a same discharge, combined of two non-adjacent spillway jets has lower scour depth and sediment height, and the length of the scouring than the jet of a combination of two adjacent jets. The width of the scouring pit, however, is in the case of overflow jets in non-adjacent jets more than adjacent jets.