Effects of Stepped Spillway Geometry on Flow Pattern and Energy Dissipation

In order to pass surplus water and inundation from upstream to downstream of dams, structure called spillway is used. Spillway and chutes are among important hydraulic structures which play a significant role in stability of dams. In some cases and when the slope is too steep to build a chute, in order to transfer water from upstream to downstream, a stepped spillway which is remarkably effective in energy dissipation is used. In the present study, in order to ascertain the effect of different parameters such as number of steps (Ns), step height (h), step length (L), and discharge in width unit (q) on energy dissipation in the simple stepped spillway, the model of Flow-3D was used, and the relationship between energy dissipation and flow critical depth in the stepped spillway was investigated. Further, the method of finite volume was used to solve the extant equations, and the model of K - epsilon was also used to investigate the flow turbulence. The results revealed that as the flow discharge increases, energy dissipation decreases and as the number of steps increases and their height decreases, energy dissipation decreases. Besides, the obtained findings were compared with the other researchers, empirical and mathematical studies and finally an acceptable coincidence was obtained.