Hydraulic analysis of skimming flows along stepped chutes
Department of Hydraulics and Sanitation University of São Paulo
Raquel Jahara Lobosco, Prof. Harry Edmar Schulz
Topics:
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1- Introduction
- The hydraulic structure
- Flow over stepped chutes
2- Air Entrainment
3- Research purposes
4-Mathematical models
- The statistical model
- Air concentration
5- Preliminary tests
- Cavitation effects
- Air distribution
- Interface capturing
7- Final considerations
The hydraulic structure:
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Picture acknowledgement: Images (2) and (3) – Engevix Company Image (1) - Stuart Longley
(2)
(3)
(1) Labyrinth spillway
Traditional Chute
Stepped Spillway
The stepped chutes:
Structure
Energy dissipation
Reduction in size Basin
Costs reduction
Enviromental impacts
Steps
Ealier areation
Increase turbulence
Decrease residual energy
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Nappe
Skimming
Large water discharges
Flow Regimes:
Air Entrainment:
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Inlet Profile
Boundary layer
Aeation
Water quality and cavitation
Research purposes:
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The statistical Model:
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Proposed by Chanson (2006)
Air concentration:
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90´
´2
2tanh1)(
hD
yKyC
Comparison with a air buble diffusion model
Proposed by Chanson (2000)
C(y) – A function of the local air concentration
Cavitation damage:
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Adaptation of Chen et al. (2002) results
Air distribution:
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Interface capturing:
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Final considerations:
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There is no simulation literature
data
Cavitation Boundary
layer region Inception
point
Acknowledgements:
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- Financial support was provided by Brazilian research funding agencies
- São Carlos School of Engineering
- Department of Hydraulics and Sanitation
- Rheology and and Turbulence Laboratory