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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : Scale effects in high-velocity air-water flows on a stepped spillway
Scale effects in high-velocity air-water flows on a stepped spillway
Author : STEFAN FELDER(1) &HUBERT CHANSON(2)
ABSTRACT
A comparative analysis of air-water flow properties was performed between two geometrically scaled stepped spillway
models with step height of 5 and 10 cm respectively. The experiments were conducted in the same large size facility with
chute slope of 26.6กใ and with the same phase-detection intrusive measurement devices. A full range of macro- and microscopic
air-water flow properties was tested for Froude and Reynolds similitudes. Significant scale effects were found in
transition and skimming flows. The present finding stressed that the notion of scale effects must be defined in terms of
explicit set of air-water flow property(ies). Some air-water flow parameter are more affected by scale effects than others,
even in large-size facilities. On one hand, the void fraction and flow bulking are not much sensitive to scale effects. On
another hand, the data analyses confirmed scale effects in terms of bubble count rate, turbulence properties and air
bubble and water droplet chord sizes, while the present investigation highlighted also scale effects in terms of further airwater
flow properties including particle clustering, inter-particle arrival times as well as auto- and cross-correlation
functions and time scales respectively. For all air-water flow properties, a close agreement was found between transition
and skimming flow outcomes. The findings highlighted that a scaling of the air-water flow properties is rarely possible and
measurements at a prototype scale are needed to identify the limitations of scaled air-water flow experiments.
File Size : 3,255,191 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 12/08/2015
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