Strong interactions between free-surface aeration and turbulence in an open channel flow

Chanson, Hubert; Toombes, Luke

doi:10.1016/s0894-1777(02)00266-2

Cited by 40 publications

(32 citation statements)

References 11 publications

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“…2B). Visual observations suggested strong mainstream-cavity flow interactions, as previously reported (Rajaratnam 1990, Chanson and Toombes 2003, Gonzalez and Chanson 2004, Bung 2009). …”

Section: Results (1) Flow Patternssupporting

confidence: 84%

“…5 stepped spillways with flat steps (Ruff and Frizell 1993, Chamani and Rajaratnam 1999, Chanson and Toombes 2003. The void fraction data showed some self-similarity except at the first step edge downstream of the onset of aeration.…”

Section: Results (2) Air-water Flow Properties At Step Edgesmentioning

confidence: 99%

“…1 and 2). A number of laboratory studies investigated systematically the air-water flow properties at step edges (Matos 2000, Chanson and Toombes 2003, Takahashi et al 2006, Carosi and Chanson 2008, Bung 2009). A few studies measured the two-phase flow properties inside and above the step cavities Chanson 2004, Felder andChanson 2011).…”

Section: Introductionmentioning

confidence: 99%

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Interaction between free-surface aeration and total pressure on a stepped chute

Zhang

Chanson

2016

Experimental Thermal and Fluid Science

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“…2B). Visual observations suggested strong mainstream-cavity flow interactions, as previously reported (Rajaratnam 1990, Chanson and Toombes 2003, Gonzalez and Chanson 2004, Bung 2009). …”

Section: Results (1) Flow Patternssupporting

confidence: 84%

Section: Results (2) Air-water Flow Properties At Step Edgesmentioning

confidence: 99%

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Interaction between free-surface aeration and total pressure on a stepped chute

Zhang

Chanson

2016

Experimental Thermal and Fluid Science

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“…Detailed air-water flow measurements highlighted large amounts of entrained air further downstream and very-strong interactions between main stream turbulence, step cavity recirculation zones and free-surface (e.g. Chanson and Toombes, 2003;Yasuda and Chanson, 2003).…”

Section: Introductionmentioning

confidence: 99%

Hydraulics of skimming flows on stepped chutes: The effects of inflow conditions?

Chanson

2006

Journal of Hydraulic Research

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Modern stepped spillways are typically designed for large discharge capacities corresponding to a skimming flow regime for which flow resistance is predominantly form drag. The writer demonstrates that the inflow conditions have some effect on the skimming flow properties. Boundary layer calculations show that the flow properties at inception of free-surface aeration are substantially different with pressurized intake. The re-analysis of experimental results highlights that the equivalent Darcy friction factor is f ∼ 0.2 in average on uncontrolled stepped chute and f ∼ 0.1 on stepped chute with pressurized intake. A simple design chart is presented to estimate the residual flow velocity, and the agreement of the calculations with experimental results is deemed satisfactory for preliminary design. RÉSUMÉLes déversoirs en marches d'escalier modernes sont typiquement conçus pour de grandes capacités de débits correspondant à un régime d'écoulement écumant dont la résistance à écoulement est principalement de traînée. L'auteur montre que les conditions d'alimentation ont un certain effet sur les propriétés de l'écoulement. Les calculs de couche de limite montrent que les propriétés d'écoulement au commencement de l'aération de la surface libre sont considérablement différentes avec une alimentation en charge. La re-analyse des résultats expérimentaux fait ressortir que le facteur de frottement équivalent de Darcy est f ∼ 0.2 en moyenne sur les chutes sans contrôle et f ∼ 0.1 avec une alimentation en charge. Un diagramme simple de conception est présenté pour estimer la vitesse résiduelle d'écoulement, et l'accord des calculs avec des résultats expérimentaux est considéré comme satisfaisant pour une conception préliminaire.

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“…Taking a collection of measurements on stepped spillways from publications [30][31][32][33][34][35], the measured velocity data are primarily focused on the region downstream of air inception. There are also limitations related to slopes or geometries of stepped spillways.…”

Section: Simulation Of Velocity Profile On Stepped Spillwaysmentioning

confidence: 99%

Application of Displacement Height and Surface Roughness Length to Determination Boundary Layer Development Length over Stepped Spillway

Cheng

Gulliver

Zhu

2014

Water

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Abstract:One of the most uncertain parameters in stepped spillway design is the length (from the crest) of boundary layer development. The normal velocity profiles responding to the steps as bed roughness are investigated in the developing non-aerated flow region. A detailed analysis of the logarithmic vertical velocity profiles on stepped spillways is conducted through experimental data to verify the computational code and numerical experiments to expand the data available. To determine development length, the hydraulic roughness and displacement thickness, along with the shear velocity, are needed. This includes determining displacement height d and surface roughness length z0 and the relationship of d and z0 to the step geometry. The results show that the hydraulic roughness height ks is the primary factor on which d and z0 depend. In different step height, step width, discharge and intake Froude number, the relations d/ks = 0.22-0.27, z0/ks = 0.06-0.1 and d/z0 = 2.2-4 result in a good estimate. Using the computational code and numerical experiments, air inception will occur over stepped spillway flow as long as the Bauer-defined boundary layer thickness is between 0.72 and 0.79. OPEN ACCESSWater 2014, 6 3889 Keywords: displacement height; surface roughness length; stepped spillway; boundary layer development; numerical simulations; logarithmic law; inception of air entrainment

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Strong interactions between free-surface aeration and turbulence in an open channel flow

Cited by 40 publications

References 11 publications

Interaction between free-surface aeration and total pressure on a stepped chute

Interaction between free-surface aeration and total pressure on a stepped chute

Hydraulics of skimming flows on stepped chutes: The effects of inflow conditions?

Application of Displacement Height and Surface Roughness Length to Determination Boundary Layer Development Length over Stepped Spillway

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