Physical Modelling and Scale Effects of Air-Water Flows on Stepped Spillways

Chanson, Hubert and Gonzalez, Carlos A. (2005) Physical Modelling and Scale Effects of Air-Water Flows on Stepped Spillways. Journal of Zhejiang University - Science A, 6 3: 243-250. doi:10.1007/BF02872325

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Author Chanson, Hubert
Gonzalez, Carlos A.
Title Physical Modelling and Scale Effects of Air-Water Flows on Stepped Spillways
Journal name Journal of Zhejiang University - Science A   Check publisher's open access policy
ISSN 1673-565X
1862-1775
Publication date 2005-03-01
Sub-type Article (original research)
DOI 10.1007/BF02872325
Open Access Status File (Author Post-print)
Volume 6
Issue 3
Start page 243
End page 250
Total pages 8
Place of publication China
Publisher Zhejiang University Press, co-published with Springer-Verlag
Language eng
Subject 290802 Water and Sanitary Engineering
0905 Civil Engineering
Abstract During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbulence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to prototypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels although little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.
Keyword physical modelling
scale effects
stepped spillways
air entrainment
air-water flow measurements
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Civil Engineering Publications
 
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Created: Fri, 05 Aug 2005, 10:00:00 EST by Hubert Chanson on behalf of Library Corporate Services