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Experimental Study of Discharge Coefficient at the Dentate Trapezoidal Labyrinth Weir
J. Meshkavati Toroujeni, A.a. Dehghani, A. ٍemadi, M. Masoudian,
Volume 25, Issue 3 (12-2021)
Abstract
One of the crucial problems that exist in the irrigation networks is the fluctuation of the water surface flow in the main channel and changes in the flow rate of the intake structure. One of the effective methods to decrease these fluctuations is increasing the weir crest length at the given width of the channel with the use of the labyrinth weirs can be achieved for this purpose. The labyrinth weir is the same linear weir that is seen as broken in the plan view. In this study, a labyrinth weir with a length of 3.72 m, three different heights of 15, 17, and 20 cm, three different shapes of dentate (rectangular, triangular, and trapezoidal), and a linear weir were used in a recirculating flume with 15 m length and 1 m width. The result showed that for a given length and height of weir, with the increasing of the upstream water head to the weir height ratio (), the discharge coefficient decreases. The results showed that by increasing weir height, the discharge coefficient decreases for a given length of the weir. Linear weir and labyrinth weir without dentate create more water depth at the upstream by 3.3 and 1.2 fold compared with dentate labyrinth weir.

Investigating the Energy Loss in the Dentated Flip Bucket and Dentated Triangular Sill Spillways in Laboratory and Numerical Conditions
M. Niroubakhsh, A.r. Masjedi, M. Heidarnejad, A. Bordbar,
Volume 28, Issue 4 (12-2024)
Abstract
The application of flip bucket and triangular launchers with different shapes has been given more attention due to safety and better energy consumption to protect the downstream bed of water structures, as well as economic benefits compared to other energy consumers. The objective of this research was to investigate the energy loss of the passing flow in the dentated flip bucket and dentated triangular sill spillways in laboratory and numerical conditions. Physical and numerical modeling was used in a rectangular flume with a length of 9 meters, a width of 0.5 meters, and a height of 0.5 meters, flip bucket, and triangular spillways with dentated with specific dimensions according to the USBR standard in different discharges intensities in laboratory and numerical conditions. The amount of energy loss in the dentated flip bucket spillway was 71.4% and the dentated triangular sill spillway was 74.8% in laboratory conditions, which showed that the dentated triangular sill spillway has a better performance in terms of energy loss than the flip bucket and triangular spillway. The results showed that the shape of the spillway geometry and the presence of the dentated at the end of the structure is an important and influential factor in the amount of energy loss of the currents passing through the dentated flip bucket and dentated triangular sill spillways, which causes more broken and compressed flow lines and, as a result, an increase in speed at the moment. The launch and finally the relative loss of energy is more downstream of the structure. After determining the better performance of the dentated triangular sill spillway in energy loss, the numerical simulation of the dentated triangular sill spillway was performed using the numerical calculation method in Flow-3D software. The results of the analyses indicated that the amount of energy loss in the dentated triangular sill spillway in the numerical calculations was 87.5%, which showed the alignment and correctness of the tests performed with the laboratory conditions.

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