Hydraulic characteristics, experimental design and numerical modeling of circular labyrinth weirs

The existing dams and reservoirs need to be revised to meet safety standards. Advances in hydrology and meteorology and the existence of longer hydrological records indicate that old dams and reservoirs that are considered to be safe need to be refurbished. For the existing reservoirs where flood control is important and the maximum water level is limited, the best method to increase the reservoir capacity is to build a labyrinth weir on the hull. The profile formed when the flow passes freely over a sharp-edged weir is called nappe flow. In labyrinth weirs, the overlap of two nappe flows creates interference between nappe flows and this reduces the weir performance. In this study, a new hydraulic design and analysis method was carried out to increase the efficiency of labyrinth weirs. In labyrinth weirs, these weirs will be circularly redesigned in order to make the areas that reduce the flow as a result of the interference of nappe flows more efficient and to ensure that the flow moves as perpendicular to the weir as possible. In circular labyrinths, the flow will be exposed to fewer intersections and will positively affect the flow rate. Circular labyrinth weirs will increase the flow-discharge capacity of the weirs by providing more flow at the same weir load as triangular labyrinth weirs. In experiments, for 3 different weir heights (P=20 cm, 30 cm and 40 cm); 27 tests were carried out for circular weirs for 9 different configurations, 9 tests were carried out for triangular weirs for 3 different configurations and 3 tests carried out for linear weirs. In total, 39 tests were carried out for weirs with circular, triangular and straight sections. In addition, in this study, numerical models of the experiments were created in computer environment by using Computational Fluid Dynamics (CFD) based programs, which are frequently used in the design of hydraulic structures in recent years.