Experimental Study of the Effect of Vertical Screen Diameter on Energy Dissipation at Downstream Vertical Drop

Screens are one of the applications at the downstream of hydraulic structures in recent years to dissipate energy and prevent erosion of the channel bed. Therefore, in the present study, vertical screens at downstream of vertical drop were used for energy dissipation and the effect of screens pore size on energy dissipation was investigated. Experiments were performed in relative diameters of 0.067, 0.133, and 0.2 with 50% porosity and relative critical depth range of 0.13 ~ 0.39. The results showed that by increasing the relative diameter of the vertical screens, the hydraulic jump formed behind the screens is submerged and reduces the performance of these screens in energy dissipation. The results also showed that increasing the relative diameter of the screens increases the depth of the vertical drop pool so that the screens with a relative diameter of 0.2 compared with the relative diameter of 0.067 increases the depth of the pool by 21%. For the relative residual energy, although increasing the diameter of the screens causes a low increase in the relative residual energy, these screens create the minimum relative residual energy and reduce the downstream Froude number range for all three relative diameters of the plates in the range 1.31 to 1.8 restricts.