American Society of Civil Engineers

Countercurrent Jet Device

by Willi H. Hager, M.ASCE, (Sr. Res. Engr., VAW, ETH-Zentrum, CH-8092 Zurich, Switzerland)

Journal of Hydraulic Engineering, Vol. 120, No. 4, April 1994, pp. 504-517, (doi:

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Document type: Journal Paper
Abstract: The flow features of a jet device mounted at the bottom of a rectangular channel and issuing a plane wall jet are studied both by computational 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 Froude 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 structures such as gates or overflow structures; and (2) the case in which excess energy must be dissipated. In case the slot Froude number should be large, combined with a low tailwater depth. The maximum efficiency of dissipation occurs for a transition from subcritical upstream to supercritical downstream flow, beyond which a conventional secondary stilling basin may be used. These features are shown to be analogous to the classical hydraulic jump.

ASCE Subject Headings:
Energy efficiency
Free flow
Hydraulic jump
Jets (fluid)
Tail water
Water levels