Hydraulic jump and energy dissipation downstream stepped weir

Abstract

Hydraulic jump can be defined as a sudden change or rise of water level because of changing the channel slope from steep to mild combined turbulent flow. This can be used for energy dissipation to reduce flow energy downstream hydraulic structure. Recent studies dealt with energy dissipation downstream hydraulic structures such as stepped weir by changing water level upstream and downstream to reduce flow energy. In this study, the focus was placed on the hydraulic jump formation downstream stepped weir and its characteristics, as well as used it as energy dissipation to reduce the residual energy that will be dissipated on stepped weir. 27 stepped weir models were tested with three different heights, slopes as well as changed number of steps for all models. It was found that the energy dissipation increased by increasing weir slope, the number of steps, and decreasing the height weir, by 20%, 20.6%, 21.8% respectively. It was also found that the energy dissipation increased when the hydraulic jump length increased, but this was not economy. The best model for energy dissipation in this study was that have lower height and greater slope and steps number. This model gives lower value of hydraulic jump length; this is more economy as it reduces the length of stilling basin which is reduces the cost of its construction downstream stepped weir or stepped spillway.