Experimental Investigation of the Scouring due to Hydraulic Jump in Screens

In this research, the applicability of the screen sheet, as an energy dissipater at downstream of hydraulic structures, has been studied to reduce the amount of scouring. For operation of the experiments, a rectangular flume with 0.3m in width, 0.45m in height and 5m in length, including a sluice gate for the flow control was used. For reducing energy of outflow from sluice gate, the screen sheets as energy dissipaters with 40% and 50% porosity were placed at distance of 1.5m from the gate. After the screen sheet, the movable beds consist of three different grain sizes of 1.8, 2.6 and 5.2 mm, with the dimensions of 1.3m in length, 0.3m in width and 11.4cm in depth were used to investigate the effect of screen on maximum dimensions of the scouring hole. The results of this study showed that the thickness and porosity of the screen and its distance from the gate are effective parameters on the lenghth and depth of scouring hole. The maximum and minimum depth and length of scouring hole were occurred in the screens with 40% porosity and double 50% porosity, respectively. So that, by increasing the screen’s porosity and thickness, the scouring whole dimension decreases. Also, by increasing the particle dimensions, the scouring hole dimension decreases.