Experimental Investigation of the Effect of Positive Slope of the Horizontal Screen on Hydraulic Characteristics of Vertical Drop

In the present study, 105 tests were carried out to investigate the effect of horizontal screen slope on hydraulic characteristics of vertical drop with the subcritical flow in upstream. The experiments were arranged in two models, plain vertical drop and vertical drop equipped with horizontal and sloping (three slopes) screens in two porosity ratios. The range of relative critical depth was from 0.07 to 0.24 the screen slopes were 7◦, 14◦, 21◦, and the screen porosities  were considered to be 40% and 50%. The relative wetted length of the screen, the relative turbulance length, the relative depth of pool, the relative downstream depth, and the relative residual energy were analyzed. In all cases, by increasing the relative critical depth, the turbulance length, pool depth, downstream depth, and relative residual energy were increased. The results showed by increasing the slope of  screen, the characteristics of the relative wetted length of the horizontal screen, relative turbulance length, and relative pool depth increases. However, the slope of screen has no effect on the relative downstream depth and the relative residual energy. It was also observed that with increasing porosity ratio of the screen, the characteristics of the relative wetted length of the horizontal screen, relative turbulance length, and relative pool depth decreases, and the relative downstream depth increases. But the porosity of screens has an insignificant effect on the relative residual energy.