Stepped spillways with aerators: hydrodynamic pressures and air entrainment
ABSTRACT The possibility of damage due to the phenomenon of cavitation leads the design of stepped spillways considering maximum specific discharges of 15 to 30 m2/s, a limit considerably lower than that practiced on smooth chutes. Aerators promote the insertion of air in the flow, allowing for the increase of specific flow rates. This work analyzes the pressures on the vertical faces of the steps and the air entrainment coefficient in the flow, through an experimental study in a physical model with a stepped chute angle of 53.13o, considering the installation of aerators in different places of the channel. Comparing the tested conditions with the natural aeration, it is concluded that the installation of the aerator does not change the magnitude of the minimum extreme hydrodynamic pressures, but anticipates the beginning of the flow aeration. A new equation is proposed to estimate the air entrainment coefficient, as well as a methodology for forecasting extreme pressures on the vertical faces of the steps, both valid in the range 3.0 ≤ Fr ≤ 6.0.
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Associação Brasileira de Recursos Hídricos
2021
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oai:scielo:S2318-033120210001002032021-03-30Stepped spillways with aerators: hydrodynamic pressures and air entrainmentFerla,RuteNovakoski,Carolina KuhnPriebe,Priscila dos SantosPrá,Mauricio DaiMarques,Marcelo GiulianTeixeira,Eder Daniel Hydraulic structures Cavitation Deflector ABSTRACT The possibility of damage due to the phenomenon of cavitation leads the design of stepped spillways considering maximum specific discharges of 15 to 30 m2/s, a limit considerably lower than that practiced on smooth chutes. Aerators promote the insertion of air in the flow, allowing for the increase of specific flow rates. This work analyzes the pressures on the vertical faces of the steps and the air entrainment coefficient in the flow, through an experimental study in a physical model with a stepped chute angle of 53.13o, considering the installation of aerators in different places of the channel. Comparing the tested conditions with the natural aeration, it is concluded that the installation of the aerator does not change the magnitude of the minimum extreme hydrodynamic pressures, but anticipates the beginning of the flow aeration. A new equation is proposed to estimate the air entrainment coefficient, as well as a methodology for forecasting extreme pressures on the vertical faces of the steps, both valid in the range 3.0 ≤ Fr ≤ 6.0.info:eu-repo/semantics/openAccessAssociação Brasileira de Recursos HídricosRBRH v.26 20212021-01-01info:eu-repo/semantics/articletext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S2318-03312021000100203en10.1590/2318-0331.262120200110 |
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Ferla,Rute Novakoski,Carolina Kuhn Priebe,Priscila dos Santos Prá,Mauricio Dai Marques,Marcelo Giulian Teixeira,Eder Daniel |
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Ferla,Rute Novakoski,Carolina Kuhn Priebe,Priscila dos Santos Prá,Mauricio Dai Marques,Marcelo Giulian Teixeira,Eder Daniel Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
author_facet |
Ferla,Rute Novakoski,Carolina Kuhn Priebe,Priscila dos Santos Prá,Mauricio Dai Marques,Marcelo Giulian Teixeira,Eder Daniel |
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Ferla,Rute |
title |
Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
title_short |
Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
title_full |
Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
title_fullStr |
Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
title_full_unstemmed |
Stepped spillways with aerators: hydrodynamic pressures and air entrainment |
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stepped spillways with aerators: hydrodynamic pressures and air entrainment |
description |
ABSTRACT The possibility of damage due to the phenomenon of cavitation leads the design of stepped spillways considering maximum specific discharges of 15 to 30 m2/s, a limit considerably lower than that practiced on smooth chutes. Aerators promote the insertion of air in the flow, allowing for the increase of specific flow rates. This work analyzes the pressures on the vertical faces of the steps and the air entrainment coefficient in the flow, through an experimental study in a physical model with a stepped chute angle of 53.13o, considering the installation of aerators in different places of the channel. Comparing the tested conditions with the natural aeration, it is concluded that the installation of the aerator does not change the magnitude of the minimum extreme hydrodynamic pressures, but anticipates the beginning of the flow aeration. A new equation is proposed to estimate the air entrainment coefficient, as well as a methodology for forecasting extreme pressures on the vertical faces of the steps, both valid in the range 3.0 ≤ Fr ≤ 6.0. |
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Associação Brasileira de Recursos Hídricos |
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2021 |
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http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2318-03312021000100203 |
work_keys_str_mv |
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