Flow and parameter optimization of tapered vane

Abstract

Abstract Submerged vanes are the hydrofoils which generate the helical currents in the flow due to the difference in pressure between the approaching flow side and the downstream side of vanes and are placed obliquely with the flow, with angles ranging from 10° to 40°. Previous studies have been done on the rectangular shaped submerged vanes but only a few studies have been reported for the submerged vanes with non-rectangular shapes. The present study aims to optimize the parameters of tapered vanes and their effect on flow structure around the vanes through numerical modelling. Numerical modelling for the present study was done in ANSYS-CFX software using the K-ω turbulence closure model to simulate the vortical flow. It was observed that maximum strength of secondary currents was obtained for angle of attack, sweep angle and relative vane height (ratio of vane height to depth of flow) of 17°, 10° and 0.48, respectively. It was also observed that in the proximity of the tapered vane, secondary currents are dominated by vortex-lift while in far-reaches, potential lift prevails. It was observed that transverse velocity was maximum for a sweep angle of 10°. Comparing the optimal rectangular vane (with angle of attack of 30) with the tapered vane (with angle of attack of 17), it was observed that the rectangular vane has a tendency to generate higher transverse velocities and hence may act as a sediment diverter to counter sediment movement while the tapered vane has a tendency to generate vortical structures over a larger distance, hence may act as a sediment managing device.