Hydraulic performance of Submerged Flow over Rectangular Labyrinth Weirs with Round Corners

This experimental study investigates the hydraulic performance of rectangular labyrinth weirs with rounded corners under both free-flow and submerged-flow conditions. Nine rectangular labyrinth weirs, varying in height and crest length, were constructed from High-Density Polyethylene Plastic (HDPE) and tested in a laboratory flume under a range of discharges. The effects of geometry and tailwater depth on discharge efficiency were evaluated. The results indicated that the discharge coefficient (CL) generally increases with the relative head ratio (HT/P) up to a certain point (0.12-0.26), after which it declines. Additionally, the discharge efficiency of rectangular labyrinth weirs with rounded corners decreases as the degree of submergence increases. Models with greater weir height were less sensitive to submergence, while those with longer crest lengths exhibited greater efficiency losses. Overall, labyrinth weirs with rounded corners maintain favorable performance under a wide range of conditions. These findings provide new insight into the influence of crest geometry and submergence on labyrinth weir hydraulics.