Investigation of Flow Energy Dissipation over Different Stepped Spillways

In this study, to investigate energy dissipation of flow overstepped spillways of different step shapes, a physical wooden model has been built in the Shahid Bahonar University’s hydraulics lab. This model with 41.41° slope has 84 cm height and 21 steps. Each step has 4 cm height, 4.5 cm width and 30 cm length. Experiments have been carried out for different types of step shapes (plain steps, end sill steps with thickness of 1, 2, 3 and 4 cm and steps with a bottom adverse slope of 15, 26, 36 and 45°). Overall, 131 experiments were done, the hydraulic parameters of flow over the model were measured and the energy dissipation of flow was calculated. Results show that the energy dissipation of flow on end sill and inclined stepped spillways are more than the plain one, it is increased by increasing the thickness of end sill or the adverse slope size. Comparison of flow energy dissipation over end sills stepped spillway and inclined type show that the inclined type has been dissipated more energy than the equivalent end sill type. Also for stepping spillway of different step shapes, flow energy dissipation decreases with increasing the flow rate. It is concluded that for a large stepped spillway with high flow rate the inclined type spillway is more effective than the other forms.