Air-Water Flows and Head Losses on Stepped Spillways with Inclined Steps

Air-Water Flows and Head Losses on Stepped Spillways with Inclined Steps

Arosquipa Nina, Yvan (University of Queensland)
Shi, Rui (University of Queensland)
Wüthrich, D. (TU Delft Hydraulic Structures and Flood Risk; University of Queensland)
Chanson, Hubert (University of Queensland)

2022

On a stepped spillway, the staircase invert profile generates some intense turbulent dissipation during the spill, associated with a significant reduction of kinetic energy, as well as strong self-aeration. The present study focused on the effects of inclined downward steps on the air-water flow properties, flow resistance, and head losses because these mostly relate to spillway design. Some physical modeling was conducted in a relatively large facility with a 45° stepped chute (1V:1H) operating with Reynolds numbers 2.8×103<Re<1×106. The presence of downward steps induced some elongated asymmetrical cavity shapes, creating a less stable cavity recirculation pattern along the entire chute, leading to different interactions with the main stream. In terms of basic air-water flow properties, the distributions of void fraction and bubble count rate presented very close results for all three stepped geometries, both qualitatively and quantitatively. The interfacial velocities did not reach any uniform equilibrium (i.e., normal flow) condition, and the fastest velocities were recorded with the 1V:2.33H inclined downward stepped chute geometry (δ =23.3° and λ/k=3), and the slowest velocities on the horizontal stepped chute (δ=0 and λ/k=2). The Darcy-Weisbach friction factor f and relative head loss δ H/Hmax were estimated in the self-aerated flow. The comparative analyses suggested that the largest total drag and head losses were observed on the stepped chute with flat horizontal steps. An inclined downward stepped design yielded lesser head losses for all investigated flow conditions, providing an important information for practical engineers designing these hydraulic structures.

Air-water flows
Head losses
Inclined steps
Physical modeling
Stepped spillways

http://resolver.tudelft.nl/uuid:afbe8485-3fa4-49ca-aad4-71c794cd3b5f

https://doi.org/10.1061/(ASCE)IR.1943-4774.0001701

2023-02-18

0733-9437

Journal of Irrigation and Drainage Engineering, 148 (11)

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

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© 2022 Yvan Arosquipa Nina, Rui Shi, D. Wüthrich, Hubert Chanson