An experimental investigation of aeration performance in stepped spillways

Baylar, Ahmet; Emiroğlu, M. Emin; Bağatur, Tamer

doi:10.1111/j.1747-6593.2005.00009.x

Cited by 55 publications

(32 citation statements)

References 31 publications

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“…The results in Figures 7a-7c, for the aeration efficiency as a function of the ratio of the length of aeration to the stepped roughness height, indicated that E20 increases as La/Ls increases. [14] stated that length of aeration increases with an increase in overall aeration efficiency; this also agrees with the statement of [20] that aeration efficiency decreases with an increase in the ratio of non-aerated length to stepped height. Aeration efficiency in Figures 8a-8c showed that it decreases as roughness Froude number Fe increases.…”

Section: Determination Ofsupporting

confidence: 78%

“…Aeration efficiency in Figures 8a-8c showed that it decreases as roughness Froude number Fe increases. Froude number is a function of the velocity; it is when the velocity is dissipated that aeration is enhanced; this agrees with the statement of [20] that aeration efficiency decreases with an increase in roughness Froude number. (11) was validated, taking the unit discharge of 26.1 L/s.m and value of aeration efficiency for two models from each chute geometry as an example, there is good agreement between them, as shown on Table 7.…”

Section: Determination Ofsupporting

confidence: 72%

“…The following three relations have been developed by [18], [19] and [20] respectively to determine the aeration efficiency of flow over stepped chutes, amongst which were: …”

mentioning

confidence: 99%

See 2 more Smart Citations

Empirical Modeling of Oxygen Uptake of Flow Over Stepped Chutes

Munta¹,

Adie²,

Abubakar³

2014

Nig. J. Tech.

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ABSTRACT ABSTRACTThe present investigation evaluates the influence of three different step chute geometry when skimming flow was The present investigation evaluates the influence of three different step chute geometry when skimming flow was The present investigation evaluates the influence of three different step chute geometry when skimming flow was The present investigation evaluates the influence of three different step chute geometry when skimming flow was allowed over them with the allowed over them with the allowed over them with the allowed over them with the aim aim aim aim of determining the aerated flow length which is a significant factor when of determining the aerated flow length which is a significant factor when of determining the aerated flow length which is a significant factor when of determining the aerated flow length which is a significant factor when developing empirical equations for estimating aeration efficiency of flow. developing empirical equations for estimating aeration efficiency of flow. developing empirical equations for estimating aeration efficiency of flow. developing empirical equations for estimating aeration efficiency of flow. conducted in the Hydraulics Laboratory of the Department of Water Resource conducted in the Hydraulics Laboratory of the Department of Water Resource conducted in the Hydraulics Laboratory of the Department of Water Resource conducted in the Hydraulics Laboratory of the Department of Water Resource Ahmadu Bello University Zaria Ahmadu Bello University Zaria Ahmadu Bello University Zaria Ahmadu Bello University Zaria----Nigeria to determined the aeration efficiency of flow over the three different chute Nigeria to determined the aeration efficiency of flow over the three different chute Nigeria to determined the aeration efficiency of flow over the three different chute Nigeria to determined the aeration efficiency of flow over the three different chute geometry at the water temperature T and at the standard temperature of 20 geometry at the water temperature T and at the standard temperature of 20 geometry at the water temperature T and at the standard temperature of 20 geometry at the water temperature T and at the standard temperature of 20 were were were were analysed using analysed using analysed using analysed using a a a a regression model regression model regression model regression model efficiency of flow efficiency of flow efficiency of flow efficiency of flow for the three chute geometry under consideration. The results revealed that the aeration efficiency for the three chute geometry under consideration. The results revealed that the aeration efficiency for the three chute geometry under consideration. The results revealed that the aeration efficiency for the three chute geometry under consideration. The results revealed that the aeration efficiency increases with an increased in the increases with an increased in the increases with an increased in the increases with an increased in the length of aeration length of aera...

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Section: Determination Ofsupporting

confidence: 78%

Section: Determination Ofsupporting

confidence: 72%

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Empirical Modeling of Oxygen Uptake of Flow Over Stepped Chutes

Munta¹,

Adie²,

Abubakar³

2014

Nig. J. Tech.

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“…Elle est souvent calculée à une température de référence de 20 °C en utilisant l'équation de GULLIVER et al (1990) : La majorité des études existantes (BAYLAR et al, 2006(BAYLAR et al, , 2007TOOMBES et CHANSON, 2005) n'intègrent pas la totalité des paramètres significatifs. De plus, les débits d'eau étudiés sont assez élevés et ne correspondent pas aux débits dans les petites rivières.…”

Section: Transfert D'oxygène Air-eauunclassified

“…Plus tard, TOOMBES et CHANSON (2005) ont étudié l'oxygénation sur un canal d'eau avec des marches d'escaliers à des dimensions proches de celles à l'échelle réelle. BAYLAR et al (2003BAYLAR et al ( , 2006BAYLAR et al ( , 2007 ont caractérisé l'oxygénation par des corrélations empiriques grâce à des mesures sur un pilote de laboratoire. Il existe d'autres approches qui ont été utilisées pour caractériser l'aération par les cascades.…”

Section: Introductionunclassified

Autoépuration en eau courante : évaluation de l’oxygénation dans les cascades en marches d’escalier

Khdhiri

Potier

Leclerc

2014

rseau

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Dans les écosystèmes aquatiques, l’oxygène dissous est consommé par les processus chimiques et biologiques de l’autoépuration (oxydoréduction, dégradation de la matière organique,...) ainsi que par la respiration des espèces aquatiques. L’autoépuration sera donc favorisée par une amélioration de l’aération et le taux d’oxygène dissous constituera un indicateur de la qualité de l’eau. Les structures hydrauliques telles que les cascades jouent le rôle de système d’aération en favorisant l’absorption dans l'eau de l’oxygène atmosphérique. Afin d’évaluer le potentiel d’aération de ces ouvrages aux faibles débits, une étude a été réalisée sur une cascade de laboratoire représentative des petits cours d’eau et équipée de plusieurs marches modulables en nombre et en taille. Le transfert d’oxygène dans les cascades est fortement dépendant de l’aire de l’interface d’échange rapporté au volume d’eau, du type d’écoulement diphasique et de la turbulence dans le fluide. Du point de vue hydrodynamique, trois régimes d’écoulement ont été identifiés pour un débit inférieur à 3 L•-s-1, deux régimes de type nappe et un régime de transition. L’efficacité du transfert d’oxygène mesurée varie de 15 % à 40 % en fonction du débit d’eau, du nombre et de la longueur des marches de la cascade. Les résultats ont montré une amélioration de l’aération avec le débit (en régime nappe) et avec le nombre de marches. Sur les différents systèmes de cascades étudiés, une relation de linéarité entre le nombre de marches et l’efficacité d’aération a été constatée. L’ajout de graviers sur les marches provoque une légère amélioration de la capacité d’aération, dépendant du niveau d’immersion des graviers. À hauteur donnée, l’augmentation de la longueur des cascades défavorise le transfert d’oxygène.In aquatic ecosystems, dissolved oxygen is consumed by the chemical and biological processes involved in natural self-purification (oxidation-reduction, degradation of organic matter,…) and by the respiration of the aquatic species. The self-purification can be enhanced by water aeration improvement and the dissolved oxygen level is thus an indicator of the water quality. Hydraulic structures such as cascades play the role of an aeration system by improving the dissolution of atmospheric oxygen in water. To estimate the aeration potential of these structures in low discharges corresponding to small natural streams, a study was realized on a laboratory cascade model equipped with a modular number of size-adjustable steps. Oxygen transfer in stepped cascades is strongly dependent on the interfacial exchange area per water volume, the multiphase flow structure and the turbulence in the fluid. From the hydrodynamic point of view, three flow regimes were identified for a flow rate lower than 3 L•s-1: two nappe regimes and one transition regime. The measured oxygen transfer efficiency varies between 15% and 40% depending on water flow rates, and the number and length of steps in the cascade. The results showed an improvement of the aeration with the flow rate (in ...

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Modeling Aeration Efficiency of Stepped Cascades by Using ANFIS

Baylar¹,

Hanbay

Ozpolat

2007

CLEAN Soil Air Water

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The physical process of oxygen transfer or oxygen absorption from the atmosphere acts to replenish the used oxygen, a process termed re‐aeration or aeration. Aeration enhancement by macro‐roughness is well‐known in water treatment and one form is the aeration cascade. The macro‐roughness of the steps significantly reduces the flow velocities and leads to flow aeration along the stepped cascade. In this paper, the aeration efficiency in stepped cascade aerators was modeled by using the Adaptive Network Based Fuzzy Inference System (ANFIS). The obtained model was tested with experimental data. Test results showed that ANFIS can be used to estimate the aeration efficiency in stepped cascade aerators.

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An experimental investigation of aeration performance in stepped spillways

Cited by 55 publications

References 31 publications

Empirical Modeling of Oxygen Uptake of Flow Over Stepped Chutes

Empirical Modeling of Oxygen Uptake of Flow Over Stepped Chutes

Autoépuration en eau courante : évaluation de l’oxygénation dans les cascades en marches d’escalier

Modeling Aeration Efficiency of Stepped Cascades by Using ANFIS

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