Energy dissipation in hydraulic jumps using triple screen layers

Abstract

In the present study, series of laboratory experiments were conducted to investigate the effectiveness of perforated screens as energy dissipators in mixed triple wall mode in the case of small hydraulic structures. The shapes of openings for each layer of screens were either circular, square or triangular. Every layer of the screen had a porosity of 45% per unit depth of the screen. The experiments were conducted to dissipate the energy for supercritical flows of Froude number F1 ranging from 3.2 to 19.3. The screens were placed vertically with the first screen 1.5 m from the sluice gate and consecutive screen at a gap of 25 mm. The experiments showed that the energy of the supercritical flows can be dissipated effectively by using perforated screens. The difference in energy dissipation between the upstream and downstream of the screen was more significant than the energy dissipation caused by classical hydraulic jumps. Comparing the results of the present study with the previous researchers it is found that the energy loss in case of present study more than the previous researchers. The relative energy loss in the present study was found to be varying from 74 to 94%. The value of the Froude number downstream of the screen, F2, was varying from 1.1 to 1.81, with an average value of 1.35. Tailwater deficit parameter, D, if found to be varying from 0.66 to 0.90.