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چکیده
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Flood discharge from dam reservoir is of utmost importance which is accomplished using weirs. The labyrinth weirs are suitable for narrow valleys as well as large floods. Labyrinth weirs have large flow passage length and consequently, high efficiency in discharging the incoming flood to the dam reservoirs. In the present study, by developing models and performing experimental tests, solutions were presented to improve the discharge coefficient and efficiency of the rectangular and trapezoidal labyrinth weirs. In other words, instead of using uniform and regular congresses in the rectangular and trapezoidal labyrinth weirs, unequal and irregular congresses were used, respectively, to increase the discharge coefficient of these types of weirs. The rectangular and trapezoidal labyrinth weirs each included 5 samples of the first type (A, D) and 5 samples of the second type (B, E) so that in the first and second types, the largest length of the congress occurred in the middle and side of the weir, respectively. Upon establishment of the mentioned models in the laboratory, different discharges were passed over the models and the flow characteristics were measured and recorded at different points, and then the discharge coefficient of the mentioned models was obtained. The solutions presented in the present study increased the discharge coefficient and consequently, the efficiency of the rectangular and trapezoidal labyrinth weirs. By using unequal and irregular congresses in the rectangular and trapezoidal labyrinth weirs instead of using equal congresses, the discharge coefficient improved on average by 40.7 and 35.3 percent, respectively.
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