Author(s): D. A. Ervine; A. R. Khan
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Keywords: No Keywords
Abstract: Aerators have been used successfully to minimise possible cavitation damage in highvelocity spillway chute flows. The concept is simple and is sketched in Fig.2. Aramp,or slot,or step-down,or a combination of allthree,is constructed in the channelbed,causing a rectangular jet to form,impinging on the spillway surface a distance Ldownstream. Shearing between the jet and atmosphere causes air to be entrained intothe jet flow,the air bubbles being transported downstream to provide cavitation protectionat least for some distance downstream of the ramp. Air entrained into the underside ofthe jet is drawn in through specially constructed air vents from the atmosphere. Thenet effect is to give a sub-atmosphere pressure at the underside of the jet(△p),andatmospheric pressure at the upper free surface of the jet. Frizzell [Ref.1]andRutschmann [Ref.2]have investigated models of air entry to the underside of the jet.Prototype structures have been fitted with aerators at many sites including,Foz-do-Areia[Ref.3],Tarbela [Ref.4],McPhee [Ref.5],Colbun [Ref.4],and Emborcaca [Ref.4],among many others.
Year: 1991