Hydraulic characteristics and energy dissipation in stepped spillways with different inclination angles

Compared with smooth spillways, stepped spillways provide superior energy dissipation. The hydraulic characteristics of stepped spillways are affected by the slope type and inclination angle of the step surface. In this study, inclination angles of 3°, 6°, and 10° were designed for both forward- and backward-inclined step configurations of stepped spillways. The renormalization group (RNG) k–ε turbulence model was used to comparatively analyze the water depth, pressure, and turbulent kinetic energy distributions along with the turbulent kinetic energy dissipation rate and Froude number of ordinary, forward-, and backward-inclined stepped spillways. The results show that for backward-inclined stepped spillways with inclination angles of 3°–10°, the energy dissipation rate increases with inclination angle and is higher than that of both ordinary and forward-inclined stepped spillways. The water flow of the forward-inclined stepped spillways is more likely to form a fixed scour on the step surface, thereby causing local erosion patterns. The flow pattern over backward-inclined stepped spillways is more complex, which helps reduce damage to the spillway. The variation pattern of the Froude number is related to flow conditions and the energy dissipation rate. Therefore, changes in the Froude number can serve as a reference when analyzing spillway flow states and energy dissipation characteristics.