Experimental Investigation of the Effect of the Geometry of Trapezoidal Arced Labyrinth Weirs on Flow Discharge Coefficient

Labyrinth weirs are structures designed for transferring large flows at low heads. In other words, labyrinth weirs are a particular type of nonlinear weirs used to control a flow as an economic and technical option. They are used when it is not possible to increase the capacity of a weir through increasing its width due to topographic conditions. These types of weirs enjoy a very high discharge capacity. As these types of weirs increase the effective length and following that the discharge efficiency, they can be used as dam weirs or water regulation structures. Considering the fact that there have been no comprehensive studies so far to investigate the weir discharge coefficient when the weir has a curved plan, in this research, some studies were conducted on trapezoidal arced labyrinth weirs with different arc radii and cycle lengths. Numerous experiments were performed using the physical modeling method to investigate the effect of the ratio of the inside apex width of the side weir cycles to the inside apex width of the middle weir cycle (w2/w1), the ratio of arc radius to the width of the middle weir cycle (R/w1), and the ratio of the length of a weir cycle to the width of the middle weir cycle (B/w1) on the weir discharge coefficient. The experiments revealed that by decreasing the inside apex width ratio of the weir cycles (w2/w1), the discharge coefficient shows an increasing trend up to 33%.