Experimental Studies on Determination of Discharge Capacity of Circular Labyrinth Weirs Located on A Straight Channel

Abstract

Labyrinth weirs are particularly well suited for spillway rehabilitation where dam safety concerns, freeboard limitations, and a revised and larger probable maximum flow have required replacement or modification of the spillway. Labyrinth weirs with multiple crest elevations can be used in spillway design to confine base flows to a section of the crest and/or satisfy discharge hydrograph requirements. Labyrinth weirs provide higher discharge capacity than conventional weirs, with the ability to pass large flows at comparatively low heads. Over past 50 years many research investigations have considered the hydraulic performance of labyrinth weirs, particularly as dependent on the geometric features. The previous work has improved the design basis for such weirs. In the present study, discharge coefficients were experimentally determined for both sharp crested semi-circular labyrinth weirs and trapezoidal labyrinth weirs of side wall angle ( α =37 0 ). A comprehensive laboratory study including 9 models was conducted to determine the discharge coefficient of the semi-circular labyrinth weirs. It was found that from this experimental study the discharge coefficient of the circular labyrinth weir is higher than that of the linear weir, but lower than that of the trapezoidal weir.