With notched on the pool elements, their performance is improve for example, compared with the simple pooled stepped spillway, the amount of energy dissipation increases 7.33%. Pool element on the steps causes some the instabilities on the center axis and sides of the steps, which causes the inception point to be moved upstream of the stepped spillway.
The results showed that the flat step configuration have the best energy dissipation performance as compared with other configurations. For that purpose, different configurations and type (height and notch) are taken into account under various hydraulic conditions at different flow regime. The localization of inception point of air entrainment is also assessed.
This study aims to consider the influence of geometric characteristics of pooled steps on the flow patterns properties, energy dissipation performance and residual head. Steps on a stepped spillway play an important role in improving energy dissipation due to the artificial roughness of the steps. Spillways are commonly constructed as floodwater release facilities in reservoir dams to transfer high energy water. Results of energy dissipation prediction using ANN, SVM, and GEP methods showed that all three models have good accuracy for estimating energy dissipation. Results showed that increasing dimensions of the edges increased energy dissipation. Results of energy dissipation prediction using ANN, SVM, and GEP methods showed that although all three models have good accuracy for estimating energy dissipation, the accuracy of ANN method with RMSE of 0.0081 and R2 of 0.9938 in the training phase and RMSE of 0.0125 and R2 of 0.9805 in the testing phase, is higher than the other two methods. Results showed that increasing dimensions of the edges increased energy dissipation, and the highest and lowest energy dissipation was related to the models with 3 and 4 serrations, respectively, Compared to the edgeless state, the 4-edge model, with relative dimension of 0.1, increased energy dissipation by an average of 20%, and the 3-edge model, with relative dimension of 0.15, by an average of 69%. Then, using artificial neural network (ANN), support vector machine (SVM), and gene expression program (GEP) methods, the accuracy of numerical models was evaluated.
#Flow free bridges 12x12 level 35 series#
For this purpose, 2, 3, and 4 serrations with 2 series of relative dimensions at the edge of the vertical drop, with a relative critical depth range of 0.2–0.35 were used for simulation.
#Flow free bridges 12x12 level 35 software#
In the present study, FLOW-3D software was used to simulate energy dissipation by a serrated-edge drop, downstream of this structure. The energy dissipation of TTLW is largest compared to vertical drop and has the least possible value of residual energy as flow increases. TTLW approximately dissipates the maximum amount of energy due to the collision of nappes in the upstream apexes and to the circulating flow in the pool generated behind the nappes moreover, an increase in sidewall angle and weir height leads to reduced energy. Hydraulics of flow over TTLW has free flow conditions in low discharge and submerged flow conditions in high discharge. The results highlighted that the numerical model shows proper coordination with experimental results and also the discharge coefficient decreases by decreasing the sidewall angle due to the collision of the falling jets for the high value of H/P (H: the hydraulic head, P: the weir height). The flow over the labyrinth weir (in both orientations) is simulated as a steady-state flow, and the discharge coefficient is validated with experimental data. To simulate the free flow surface, the volume of fluid (VOF) method, and the Renormalization Group (RNG) k-ε model turbulence were adopted in the FLOW-3D software. In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal-triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to the reservoir discharge channel.
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