Experimental Investigation of Energy Dissipation in Vertical Drops Equipped with a Horizontal Screen under Supercritical Flow

In this study, horizontal screens were used in the edge of vertical drops, as an excessive energy dissipater of flow, to increase dissipation of energy in vertical drops with the supercritical flow at upstream. Experiments adjusted for a simple vertical drop and a drop equipped by screens with two porosity values and three openings of the upstream sluice gate. During the experiments, it was observed that the horizontal screen after drop increased the air entrance and turbulence in the pool due to dividing the falling jet into a large number of small vertical jets. The results indicate that using these plates in the vertical drops increases the relative depth of downstream, relative depth of pool and relative energy dissipation as compared to a simple vertical drop. Also, results showed by increasing the upstream Froude number and decreasing the relative critical depth, the relative energy dissipation increases. However, the porosity of screens has not a significant effect on energy dissipation. Investigation and comparison of the results corresponded to the simple vertical drops and the ones equipped with screens indicated that incorporating the horizontal screens in these structures eliminate or decrease the length of stilling ponds.