Jet Flow on Stepped Spillways

Abstract

This technical note presents a method to estimate the energy loss on stepped spillways for the jet‐flow regime, which occurs when the ratio of the critical depth yc to the height of the step h is less than approximately 0.8. It introduces the concept of α, the proportional energy loss per step, and using the extensive experimental results of Horner, α; was evaluated. It was found that α is a function of yc/h and h/l, where l is the length of the step; and an equation has been developed that describes this variation. It was also found that the energy loss on a stepped spillway with a large number of steps can be very significant in the jet‐flow regime. It also appears that for skimming flow, which occurs for yc/h larger than about 0.8, the average energy loss per step would be less than that for jet flow.