Improving Energy Dissipation on Stepped Spillways (Numerical Simulation)

The transfer of water over the dam spillway produces high levels of kinetic energy, and using a stepped spillway increases the energy dissipation rate in the waterway. Thus, this study has adopted the testing of four different stepped spillway models. The first model is the traditional model (flattened steps spillway), and the other three models have steps with triangular sills at different locations along the steps. The flow and energy dissipation behaviour is tested using the Flow-3D. The results have showed that the triangular sills have contributed to enhancing the dissipation of energy and thus its effect on reducing the size of the stilling basin. In addition, the results show that the proposed model 4 has been the most efficient in terms of its energy dispersion by 28%, and it also has an effect in obtaining the lowest amount of turbulent kinetic energy value by 66% compared to the flattened spillway. Model 4 shows the best performance in static pressure values that assess formation cavitation, damage, and erosion of the structure's floor by inappropriate flow behaviour and instability. By reducing the released discharge, the highest length of the none-aerated zone flow has been reduced compared to the flattened spillway. In addition, the results get empirical equations to extract the length of the non-aerated zone.