Investigating the Efficiency of Trapezoidal Labyrinth Weirs with Equal and Unequal Indentation Lengths

Weirs are one of the most important hydraulic structures used in dams, which are built for safe discharge of flood flows. In order to increase the weir discharge capacity, labyrinth weirs are used in small openings. In the present study, 2 different geometries in the design of trapezoidal labyrinth weirs with equal (B model) and unequal (quintet F models) Indentation lengths were investigated in a laboratory and for different flow rates. Has been The experiments were conducted with the aim of reducing the interference of water blades and increasing the efficiency and discharge coefficient (C) of the mentioned weirs. The results show that; In most cases, the discharge coefficient of labyrinthine weirs with unequal Indentations is higher than that of equal Indentations. The highest weirs discharge coefficient is when the Ht/P ratio is at its lowest value. In this situation, by increasing the volume of water passing through the flume until the Ht/P ratio is less than 0.3, the trend of changes (C) in relation to Ht/P is decreasing, and from this point on, with the increase of the Ht/P ratio to more than 0.3, in all the built samples of F models, due to the interference of the water blades and also due to the absorption of the weir Indentations, the changes in C are very insignificant compared to the increase in the Ht/P ratio, and practically the weir discharge coefficient in discharge the above is almost constant and unchanged. In other words, in unequal labyrinth weirs where the rate of decrease in the collision length of their blades is between 15 and 27.5%, the discharge coefficient compared to labyrinth weirs with equal Indentation length has increased at least 32.4% and at most 35.3%.