Energy dissipation and geometry effects over stepped spillways

The energy dissipation process is the major significant point in the design of hydraulic structure. The dissipation of high energy on stepped weirs prevents any damage in the weir itself and channels the energy ownstream to reduce the stilling basin size. In this study, four physical models are used to evaluate the impact of adding end sills that have a quarter circle shape at step edges. The amount of energy loss on weirs under different flow regimes is investigated by experimental work. Stepped weirs have a suitable number of steps and two different ratios of the width to height (2.22, and 2.40). The scale of the physical models is 20:1. The outcomes of the dimensional analyses refer to the critical depth for flow in weirs to the height of step yc/h, the end sill radius, and the number of steps N are more effective parameters than others in the energy loss process. Moreover, for small values of yc/h, the energy dissipation is the greatest. Any increase in yc/h leads to a decrease in the energy dissipation, while the energy dissipation increases with the number of steps (N).