A study of the effects of the longitudinal arrangement of submerged vanes on river configuration and impoundment efficiency and decreasing sedimentation near the intake structures

摘要

Constructing intake structures in order to deviate a part of flow from the rivers, causes some changes in hydraulic conditions of flow in the front of the intake port. The changes as flow in river bends, reinforces the secondary flows, cause sedimentation in the intake port and erosion in the bank-facing intake. Submerged vanes have been used for different purposes such as reducing erosion in river bends, bank stabilization, increasing impoundment efficiency and so on. The vanes are installed with an angle of 15°-25° to the flow direction and their initial height being about 20%-to 50% of the flow depth. In this study, the possibility of use submerged vanes to control and direct the flow and river Talweg toward the intake port with different longitudinal arrangement has been investigated. Three longitudinal distances 3H, 4H and 6H (H, being the initial height of the vanes) have been considered and the experiments have been done for the regular and zigzag arrangement for different discharges. The results show that: using submerged vanes in the longitudinal distance (3H-6H) in regular and zigzag arrangement, make it possible to direct the Talweg toward the intake port and with the use of the vanes, a trench is made toward the intake in which the impoundment efficiency increases by 50%-80% in regular arrangement and 25%-50% in zigzag arrangement. Submerged vanes can also reduce the sedimentation by 40% in comparison with intake without vanes.