COUNTERCURRENT JET DEVICE

The flow features of a jet device mounted at the bottom of a rectangul ar channel and issuing a plane wall jet are studied both by computatio nal and experimental means. It is found that the countercurrent jet is able to lift the water dynamically, and that the difference of water levels in the up- and downstream portions depends mainly on the slot F roude number and the relative height of slot. From the practical point of view, two applications may be considered: (1) The case in which a difference in water level should be created without usual hydraulic st ructures such as gates or overflow structures; and (2) the case in whi ch excess energy must be dissipated. In case 2 the slot Froude number should be large, combined with a low tailwater depth. The maximum effi ciency of dissipation occurs for a transition from subcritical upstrea m to supercritical downstream flow, beyond which a conventional second ary stilling basin may be used. These features are shown to be analogo us to the classical hydraulic jump.