Energy dissipation for supercritical flows by using screens in double-wall mode.

In the present study, the performance of the perforated screens in double-wall mode was investigated through laboratory experiments. Screens had circular, square, and triangular shapes of openings with a porosity of 45% per unit depth of the screens. The screens were placed vertically with the first screen placed at a distance of 1.5 m from the sluice gate and second screen at a gap of 25 mm downstream of the first screen. The supercritical flow through the sluice gate collided with the screens and forced hydraulic jump was created in the immediate upstream of the screens. Froude number F₁ of the supercritical flows approaching the screens varied from 3.20 to 19.40 in all experiments. The relative energy dissipation between the screens upstream and downstream was more than that of the classical hydraulic jumps. Furthermore, it was found that this relative energy loss in the case of the double screen having different shapes of openings in the screens was marginally more than that of the double screen, both having similar shapes of openings. The value of the downstream Froude number of the screen, F₂, varied from 1.01 to 1.91, with an average value of 1.41. [ABSTRACT FROM AUTHOR]