Investigation of effect of anti-vortex plates on discharge capacity and scour depth at the labyrinth side weirs

Side weirs located on channels or rivers have attracted considerable interest and research effort. Side weirs are commonly used in flood channels, irrigation channels, land drainage, and urban sewerage systems by flow diversion or intake devices. There are a lot of studies related to the discharge coefficient of the side weirs. There are only a few studies about labyrinth side weirs due to the fact that Labyrinth side weirs are a new side weir type. Labyrinth weir is an overflow weir, folded in plan view to provide a longer total effective length for a given overall weir width. These weirs have advantages compared to the straight overflow weir and the standard ogee crest. The discharge coefficient of the labyrinth side weir is 1.5 to 5.0 times higher than the conventional side weir. Moreover, nappe load over the weir is less than that of the conventional side weir. Most previous studies focused on rectangular and triangular side weirs in straight channels. The same, however, is not true for labyrinth side weirs. In the previous studies, the discharge capacity and water surface profile of side weirs has been studied as experimental and numerical. The present study investigates the effect of the (anti-)vortex structures on the discharge coefficient of trapezoidal labyrinth side weirs located a rectangular main channel for subcritical flow regime and free overfall and, in particular, the effect of Froude number F1, the dimensionless weir crest height p/h1, the dimensionless weir width L/B, the dimensionless effective side weir length L/Le and the sidewall angle α on the discharge coefficient. To the best of our knowledge, no previous work has reported on the effect of vortex structures at the trapezoidal labyrinth side weirs. In the current study, 537 experimental runs has been conducted using the different side weir openings, the different crest heights and the different anti-vortex structures. Moreover, clear water scour experiments have been made in order to see the effect of the anti-vortex on maximum scour depth using Type-2, Type-3 and Type-6 vortex structures. In the experiments, the crest height is P=12 cm, the side weir opening is L=40 cm and the side wall angle is α=90 degrees and the different flow intensities (V/Vkr) have been considered.