Air-water flow properties in stepped chutes with modified step and cavity geometries

Zhang, Gangfu; Chanson, Hubert

doi:10.1016/j.ijmultiphaseflow.2017.11.009

Cited by 10 publications

(3 citation statements)

References 20 publications

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“…The stepped spillways are generally uniform in width along the flow channel. With increasing discharge, three distinct flow regimes of nappe, transition and skimming have been found, and their flow performances, energy dissipation efficiencies, pressure characteristics and air-water flow properties have been thoroughly investigated [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Effects of Converging Sidewalls on Skimming Flow over Converging Stepped Spillway

et al. 2022

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A numerical study is conducted for converging stepped spillways with various spillway slopes, sidewall convergence and flow discharges to understand the influences of converging sidewalls on skimming flows. Compared with the traditional uniform-width stepped spillway, the converging sidewall changes the skimming flow features by generating standing waves on the free-surface, curving the mainstream streamlines and squeezing and distorting the bottom rotations. For free-surface, mainstream and bottom rotations, the width of disturbed regions by the converging sidewall varies, with that for bottom rotations being 1.5 times that for mainstream and 3 times that for free-surface. The variation rules of disturbed region widths along the spillway are obtained, and the maximum widths increase as the convergence angle and incoming flow discharge increase, and the spillway slope decreases. Three equations are established for predicting the maximum widths of disturbed regions for free-surface, mainstream and bottom rotations of skimming flow. Since the disturbed region of skimming flow generated by the converging sidewall is characterized by strong standing waves, high flow velocity and low air concentration, appropriate engineering measurements should be taken for the disturbed region to meet the challenges to overtopping, energy dissipation and cavitation control.

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Section: Introductionmentioning

confidence: 99%

Effects of Converging Sidewalls on Skimming Flow over Converging Stepped Spillway

et al. 2022

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“…Zhang and Chanson examined the air-water properties on a stepped spillway with modified steps and cavities [5]. It was concluded that partial cavity blockages have little effect on air entrainment, but were linked to an increased presence of large-scale structures in the overflow.…”

Section: Introductionmentioning

confidence: 99%

Effects of Inclination Angles on Stepped Chute Flows

Yang

2020

Applied Sciences

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Owing to its effective energy dissipation and aeration, a stepped spillway is commonly used for flood release in hydraulic projects. Its conventional design features horizontal step surfaces. Designed for certain flow rates, it does not function satisfactorily at larger discharges. To improve this, layouts with inclined step surfaces, both downward and upward, are proposed. Computational fluid dynamics (CFD) modelling in 3D is performed to examine and compare their flow properties in the skimming flow. The results suggest that a shift from a downward to an upward layout leads to a gradual decrease in the flow velocity at the chute end; the latter exhibit higher energy dissipation efficiency. Moreover, equations are developed to estimate the velocity and energy loss. The flow velocity in the developing zone, described by a power law, shows a decline with an increase in the angle of inclination. The downward layout is subjected to somewhat higher risk of cavitation if implemented in a prototype. The extreme pressure loads acting upon an upward layout are larger, and a correlation is proposed for its prediction. On an inclined surface, either upward or downward, the pressure demonstrates an S-shaped distribution. On a vertical surface, the flow pressure increases, after an initial decline over a short distance, towards the chute bottom.

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“…Flows on stepped chutes are characterized by strong energy dissipation and complex interactions between air and water entities within the flows downstream of the inception point of free-surface aeration (e.g. Gonzalez and Chanson, 2008;Bung and Valero, 2016;Felder and Chanson, 2016a;Zhang and Chanson, 2018). Stepped spillways for flood mitigation purposes are typically designed for maximum flow conditions, which take place in the skimming flow regime.…”

Section: Introductionmentioning

confidence: 99%

Nappe flows on a stepped chute with prototype-scale steps height: Observations of flow patterns, air-water flow properties, energy dissipation and dissolved oxygen

Felder

Geuzaine

Dewals

et al. 2019

Journal of Hydro-environment Research

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Air-water flow properties in stepped chutes with modified step and cavity geometries

Cited by 10 publications

References 20 publications

Effects of Converging Sidewalls on Skimming Flow over Converging Stepped Spillway

Effects of Converging Sidewalls on Skimming Flow over Converging Stepped Spillway

Effects of Inclination Angles on Stepped Chute Flows

Nappe flows on a stepped chute with prototype-scale steps height: Observations of flow patterns, air-water flow properties, energy dissipation and dissolved oxygen

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