Effects of step pool porosity upon flow aeration and energy dissipation on pooled stepped spillways

Felder, Stefan and Chanson, Hubert (2014) Effects of step pool porosity upon flow aeration and energy dissipation on pooled stepped spillways. Journal of Hydraulic Engineering, 140 4: 04014002.1-04014002.11. doi:10.1061/(ASCE)HY.1943-7900.0000858

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Author Felder, Stefan
Chanson, Hubert
Title Effects of step pool porosity upon flow aeration and energy dissipation on pooled stepped spillways
Journal name Journal of Hydraulic Engineering   Check publisher's open access policy
ISSN 0733-9429
Publication date 2014-04-01
Sub-type Article (original research)
DOI 10.1061/(ASCE)HY.1943-7900.0000858
Open Access Status File (Author Post-print)
Volume 140
Issue 4
Start page 04014002.1
End page 04014002.11
Total pages 11
Place of publication Reston, VA, United States
Publisher American Society of Civil Engineers
Language eng
Formatted abstract
The hydraulics of stepped spillways with flat steps has been studied for the last three decades, including for embankment dam slopes, but studies of alternative stepped designs are limited. In this study, a pooled stepped spillway was investigated in a relatively large-size facility, and three different pool wall porosities were tested. The flow patterns, the macro- and microscopic air-water flow properties, and the energy dissipation performances were recorded; the results were compared with the flat stepped spillway design for the same chute slope (θ=26.6°). The investigations highlighted a close agreement between air-water flow properties on the configurations in terms of void fraction, turbulence levels, bubble count rate, and chord sizes. The interfacial velocity distributions showed larger interfacial velocity on the pooled step configurations of approximately 5–10% linked with a reduced flow depth. On the porous pooled stepped spillways, the interfacial velocities within the cavity highlighted the flow through the pores and the reduction in cavity recirculation. The porous pooled weir reduced the form drag, and the residual energy was approximately 1.5–2 times larger on the porous pooled stepped chute with Po=31% and approximately 1.3 times larger on the porous steps with Po=5% compared with the flat stepped chute. The flat step design appeared to be the most advantageous in terms of flow stability and energy dissipation performance.
Keyword Porous pooled steps
Pooled steps
Stepped spillway
Flow aeration
Energy dissipation
Flow resistance
Physical modelling
Air-water flows
Stepped spillways
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Civil Engineering Publications
Official 2015 Collection
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Citation counts: TR Web of Science Citation Count  Cited 8 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 6 times in Scopus Article | Citations
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Created: Fri, 21 Mar 2014, 20:26:55 EST by Hubert Chanson on behalf of School of Civil Engineering