Author(s): Jahani Matin, Jabbari Ebrahim, Sarkardeh Hamed, Marosi Morteza
Linked Author(s): Hamed Sarkardeh
Keywords: High dam, pier, vortex, spillway, numerical and physical modeling
Abstract:
In this study, the effect of vertical inclination of the piers on the flow pattern and rating curve of dam spillways was studied using numerical and physical models. Experiments on the flow pattern through vertical piers were conducted to produce measurement data of the discharge, flow depths and velocities over the spillway. Then sensitivity analysis of grid resolutions in the CFD simulations was performed for the vertical piers model. The performance of the CFD simulations with the selected grid resolution was examined and validated by comparing the results of the simulation with the measured data for vertical piers model. Generally, the simulation results were found to be in good agreement with the measured values, with an average relative deviation of less than 10%. Finally, the effect of vertical inclination of the piers on the flow pattern and rating curve was investigated using CFD simulations. Flow conditions between a vertical pier and two inclined piers (81° and 64° inclination from horizontal) were evaluated. Results showed that a longitudinal inclination of nose of the pier leads to improve the approach flow conditions. Assessing the performance of the 64° inclination shows that this scenario was suitable to pass smoothly flow through the piers and omitting the cross waves and caused the minimum separation along the piers and approach channel. To illustrate the performance of the 64° inclination, flow cross section was plotted which implies uniformity and no cross waves through the approach channel. Comparison between three inclination modes showed that with increasing 28% of vertical inclination of piers, depth averaged velocity in approach channel decreased to 16% and discharge coefficient of spillway increased approximately to 10% and as flow depth in approach channel decreases, discharge coefficient increases. To conclude, as the inclination increases, shock waves reduced and horizontal vortices eliminated. (2625, 70, 313)
Year: 2017