Author(s): H. Chanson; Luke Toombes

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Keywords: Stepped spillway; transition flow regime; free-surface aeration; chaotic flow pattern; experimental study

Abstract: Stepped spillway flows may behave as a succession of free-falling nappes at low flows and as a skimming flow at large discharges. However there is a range of intermediate flow rates characterised by a chaotic flow motion associated with intense splashing: i.e. the transition flow regime. Detailed air-water flow properties in transition flows were measured in two large experimental facilities. The results provide a complete characterisation of the air concentration, velocity and bubble count rate distributions. They highlight some difference between the upper and lower ranges of transition flows in terms of longitudinal free-surface profiles and air concentration distributions. Overall a dominant feature is the very-strong free-surface aeration, well in excess of observed data in smooth-invert and skimming flows.

DOI: https://doi.org/10.1080/00221686.2004.9641182

Year: 2004