Effect of Perforated Inclination and Height of Sill on Maximum Scour Depth and Energy Losses Downstream a Sluice Gate

Screens have proven to be an effective choice for decreasing scour downstream of small hydraulic structures. This paper studies experimentally the performance of an inclined perforated sill with a fixed porosity of 41.1% and varied height. Six different relative heights (from 0.34 to 2.25) and inclination angles of screens (30 ˚, 60 ˚, 90 ˚, 120 ˚, and 150) were tested under different flow conditions. The presence of a screen in the stilling basin reduced the maximum scour depth until the relative screen height was less than two compared to the no-screen case. A relative screen height greater than two increases the maximum scour depth. The best relative height of the screen is found to be approximately unity from the scour point of view. while the relative energy loss increases positively with the relative screen heights. Moreover, the vertical angles provide the best conditions for scour and energy dissipation. Finally, an empirical equation was developed to predict the maximum scour depth. A good agreement was found between the results of the predicted equation and the experimental results, with a mean relative error of about 6%.