Leila Davoodi1 and Mahmood Shafai Bejestan2
Abstract
Construction of the intake structures to divert some portion of flow from a main channel causes variations of flow conditions at the intake entrance. Due such conditions the sediment can enter the intake. An effective measure to control the entry sediment is the use of submerged vanes. Most of previous studies in this regards have been conducted in a rectangular flume cross section. Since most of the main channels are in trapezoidal cross section and the effect of channel cross section on submerged vane criteria are not known, this study was conducted. In this study, four difference longitudinal distances equal to 4H, 6H, 8H and 10H between vanes were tested under four different flow conditions (Froude number equal to 0.45, 0.55, and 0.60 and 0.66). In all tests the flow discharge ratio was kept constant equal to 7.5 percent. The results of the study shows that submerged vanes can modify the flow patterns in front of intake in such a matter that entry sediment decreases up to 31%. Analyses of data also show that the entry sediment is minimum when the distance between vanes is equal to 8H.