The Effect of Diversion Angle on Sediment Control at Intake Mouth in U-Shaped Bend with Skimming Wall and Sill

One of the main goals of diverting water from bend of river is diversion the maximum flow discharge with the minimum rate of sediment to the intake mouth. Therefore, the position and diversion angle of lateral intakes in river bend with sediment control structures, are the major parameters that must be considered.In this study by experimental investigation in a U- shaped channel using compound structures of sill and 10 skimming wall in three diverted flow percentages of 17, 21 and 26, the effect of diversion angle on rate of sediment entering the intake, was investigated. The results showed that with decreasing of the angle of intake, the inflow Froud number decreases. Also with increasing the angle of intake from 45 to 75 degrees, the rate of sediment entry to intake increases, so that by combining of sill and skimming wall 10ᵒ, the sediment transportation into intake mouth decreases more in comparison with basic state. By increasing the angle of flow diversion in all percentages of flow diversion, the width of separation zone at water surface decreases. By investigation of power of secondary flow along the intake mouth it was found that in all experimental states, decreasing the angle of flow diversion from 75 to 45 degrees, causes less decreased power of secondary flow and consequently less sediment entry into the intake mouth.