11/18/2023 0 Comments Concrete flume with energy dissipators(2011) used genetic algorithms to determine the optimal dimensions of the Sarough Dam spillway located in West Azerbaijan province, Iran. For the five cases, the Darcy-Wiesbach roughness coefficient ( f) varied from 0.12 to 0.37, which was consistent with the previous work of Felder & Chanson (2009) in which f varied from 0.1 to 0.35. Although the results showed that the number of steps did not have much effect on the residual downstream energy, a spillway with 10 steps of 10 cm height had less residual energy and thus more energy dissipation. Five different cases were considered for the step heights and the residual energy downstream of the spillways were measured. (1999) has also been reported.įelder & Chanson (2011) performed experiments on a physical model of a stepped spillway with a height of 1 m and a slope of 26.6°. Determining the amount of energy loss by indirect methods using the conjugate depth of the hydraulic jump by Tazzi (1992) and Pegram et al. Matos & Quintela (1994) did not consider the use of the aerated water depth downstrem of a spillway to calculate energy loss to be correct they found that because of the use of aerated water depth instead of pure water depth, the amount of flow energy dissipation was overestimated. Consequently, they considered the Chanson (1994a, 1994b)'s conclusions to be questionable. In response, Matos & Quintela (1994) identified the error caused by air etrainment in the spillway and its effects on measuring flow depth. However, according to Chanson (1994b), in long stepped spillways with established flow, the flow energy loss with the skimming flow exceeds that of nappe flow. (1992), Chamani & Rajaratnam (1999), and Matos & Quintela (1994), have argued that energy dissipation in the nappe flow regime is greater than in the skimming flow regime. Many researchers, including Peyras et al. In Equation ( 1) l is the horizontal length of the step. Using multiple regressions, some useful relations for determination energy dissipating are obtained. However, for a constant discharge over a stepped spillway, increasing spillway slope, and increasing the number of steps will increase the energy dissipation. The spillway slope and step number have less impact on the rate of energy dissipation. It was found that the two most important dimensionless factors influencing energy dissipation are the Froude number and q 2/( gH dam 3). The purpose of this research is to investigate energy dissipation rate in spillways with different slopes. Several physical models have been constructed in order to measure the energy dissipation. Two different-sized flumes were used in the experiments (25 and 50 cm wide). The crest of the spillways have standard Ogee profiles and a constant slope extends from the crest to the spillway toe. In the present study, nine physical stepped spillway models with slopes of 15, 25, 45° and with a number of steps varying from 5 to 50 have been constructed. When energy is dissipated by the steps, it reduces the energy reduction that otherwise must occur at the toe of the spillway. This type of spillway is attractive for water resource management because it dissipates energy that is within the flow. In a stepped spillway, the spillway face is provided with a series of steps from near the crest to the toe.
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