Submerged vane performance in strongly curved narrow channel bends.

Abstract

Submerged vanes are thin flow-training structures that protrude above the channel bed to a height of approximately 0.2 to 0.5 times the flow depth. They have lengths of 1 to 4 times their height, and are typically angled between 5 and 30 degrees to the free-stream flow direction (counterclockwise, when viewed in plan, in a bend turning to the right). The vanes induce a secondary current which may be harnessed to counteract the centrifugally-induced helicoidal flow in channel bends. A reduction in the strength of the helicoidal current will in turn lead to a corresponding reduction in outer bank erosion. Physical model testing was performed to determine the effects of several parameters which affect submerged vane performance, namely: submerged vane height H, length L, angle to main flow direction alpha, vane streamwise spacing deltas, vane transverse spacing from outer bank deltan, and bend angle ϕ. Two bend angles were examined in this study. The majority of testing was performed in a 90° bend, and a limited number of tests were performed in a 135° bend with the same radius. (Abstract shortened by UMI.)