Experimental study of the effect of horizontal screen diameter on hydraulic parameters of vertical drop

Abstract

The horizontal screen is one of the energy dissipater structures used on the brink of vertical drop. These structures increase the energy dissipation and the turbulence in the flow by causing air entrainment. In the present study, the effect of the diameter of the screen with constant porosity at three different diameters on the hydraulic parameters of the vertical drop was investigated. The experiments were performed in the relative critical depth range of 0.13 to 0.39. The results showed that by increasing the relative diameter of the horizontal screen, the relative wetting length and turbulence length increased, the residual energy remained constant and the pool depth decreased. Compared to the stilling basin, the horizontal screen significantly reduces turbulence length and residual energy. The results also showed that the application of horizontal screens at the brink of the drop, with and without a downstream rough bed, could be a suitable alternative for a stilling basin. HIGHLIGHTS The horizontal screen is one of the energy dissipator structures used on the brink of vertical drop and increases the energy dissipation and the turbulence in the flow by causing air entrainment.; The diameter of the screen holes plays a role in increasing the mixing length.; Vertical drop equipped with a horizontal screen reduces the residual relative energy by 30% compared to the stilling basin.;

Keywords

• air entrainment
• energy loss
• mixing length
• screen diameter
• vertical drop