Turbulence characteristics in skimming flows on stepped spillways

The stepped spillway design is characterised by some increase in the rate of energy dissipation on the chute associated with a reduction of the size of the downstream energy dissipation system. This study presents a thorough investigation of the air-water flow properties in skimming flows with a focus on the turbulent characteristics. New measurements were conducted in a large-size facility (theta = 22 degrees, h = 0.1 m) with several phase-detection intrusive probes. Correlation analyses were applied to estimate the integral turbulent length and time scales. The skimming flow properties presented some basic characteristics that were qualitatively and quantitatively in agreement with previous air-water flow measurements in skimming flows. Present measurements showed some relatively good correlation between turbulence intensities Tu, and turbulent length and time scales. They illustrated large turbulence levels and large turbulent time and length scales in the intermediate region between the spray and bubbly flow regions.

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