Innovative Energy-Dissipating Hood

Fixed-cone valves are generally used to regulate flow under medium to high head conditions because of their ability to safely and efficiently pass the flow. By design, fixed-cone valves, also known as Howell–Bunger valves, emit a large-diameter conical spray. The spray is effective in spreading and dissipating energy, although in some conditions where space is limited, it may be desirable to contain the spray. Containing the spray may be achieved by using a hood; however the result is a high velocity hollow jet that focuses the energy in the stilling basin. Depending on the size of the stilling basin downstream of the valve and the sensitivity to environmental factors, it may be necessary to dissipate some energy of the concentrated jet prior to impingement in the stilling basin. This paper discusses the development of a baffled hood that is capable of dissipating over 92% of the power available upstream from the fixed-cone valve. Practicing engineers will find the information of this study helpful in assessing alternative means of dissipating energy when utilizing fixed-cone valves to regulate and control discharge.