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Air–water flows and free-surface profiles on a non-uniform stepped chute

Author(s): Stefan Felder; Hubert Chanson

Linked Author(s): Stefan Felder, Hubert Chanson

Keywords: Air–water flow; free-surface profiles; non-uniform steps; physical modelling; stepped spillways; turbulence

Abstract: Comparative experiments were conducted between uniform and non-uniform stepped spillway profiles in a large-size laboratory facility. For each stepped configuration, the air concentration distributions matched the advective diffusion equation and the interfacial velocity was well correlated with a power law. A comparison of the air–water flow properties showed small differences in terms of number of entrained air bubbles, chord sizes and turbulence characteristics between the different configurations. For the non-uniform steps, larger flow instabilities and stronger variation in the air–water flow properties were observed. Further some non-intrusive measurements were performed with acoustic displacement metres to characterize the free-surface profiles, free-surface fluctuations and free-surface wave celerity in both non-aerated and aerated flow regions. The experiments highlighted a close agreement between experimental data and theoretical predictions in the non-aerated flows and with conductivity probe data in the aerated flows. The non-intrusive technique was suitable for measuring the free-surface characteristics on stepped chutes, especially in the non-aerated flow region.


Year: 2014

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