American Society of Civil Engineers

Efficiency of a Vortex Chamber with Horizontal Bottom under Supercritical Flow

by Katrin M. Motzet, (No affiliation information available.) and Franz Valentin, (Institute of Hydromechanics and Hydrology, Techniusche Universtitát München, Arcisstraße 21, 80333 München, Germany)
Section: Hydraulics, pp. 1-11, (doi:

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Document type: Conference Proceeding Paper
Part of: Global Solutions for Urban Drainage
Abstract: Whenever fluid flowing in an open channel or partially filled pipe has to be transferred almost vertically to a lower level, a vortex drop shaft is a possibility which is finding increasing application in practice. One main component of the vortex drop shaft is the vortex chamber. Depending on the approaching flow usually two kinds of constructions are in use. While for the subcritical flow the bottom of the vortex chamber is horizontal for the supercritical flow the bottom is normally constructed with a longitudinal slope. The construction of a sloped bottom is much more costly than a horizontal bottom and sometimes it is not possible to predict whether the flow in the approaching channel is subcritical or supercritical. Therefore, at the Institute of Hydromechanics and Hydrology at the Technische Universität München model tests were performed to study what happens when a vortex drop shaft originally constructed for subcritical flow is used for supercritical flow. It turned out that for lower discharges the maximum of the developing shock wave can be calculated with common calculation types for supercritical flow. Further on it can be seen that the entering jet will not be completely deflected in the vertical conduit, but turns at 360° and influences itself. For a certain inflow quantity the interference is so intense, that a hydraulic jump develops and the water level increases slower. The water level depending on the approaching flow is illustrated in diagrams for four different slopes of the intake pipe.

ASCE Subject Headings:
Critical flow