Hydraulic model of the energy-dissipating stilling basin of a Howell-Bunger valve

The traditional design for a Howell-Bunger stilling basin has a valve discharging at atmospheric pressure, a channel with a 30° bottom slope and an end still. The design produces an adequate dissipation of energy and has been tested thoroughly in laboratory and field conditions. However, in this study, the valve is submerged and discharges water under an 8 m pressure head. This configuration produces a completely different hydraulic flow pattern, with high surface agitation and incomplete energy dissipation. This paper describes the experimental model and prototype and gives conclusions and recommendations for stilling basin behaviour across the entire range of flows tested.