Study of the Inception Length of Flow over Stepped Spillway Models

Munta, S; Otun, J. A.

doi:10.4314/njt.v33i2.6

Cited by 6 publications

(13 citation statements)

References 7 publications

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“…In the pooled stepped spillway, the mean air concentration is larger than that in the flat stepped spillway. Munta and Otun [25] On increasing the discharge, the length of the non-aerated flow zone and the risk of cavitation both increase. The zone near the inception point is closely related to cavitation damage.…”

Section: LImentioning

confidence: 99%

Effect of Height and Geometry of Stepped Spillway on Inception Point Location

2019

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Air entrainment in a stepped spillway is very important to protect the spillway from cavitation damage. The inception point is the location where air starts entering the non-aerated flow zone. The inception point location depends on different parameters, such as the discharge, step height, and step shape. In this paper, various stepped spillways, including flat steps, pooled steps, and round steps with different step heights were numerically simulated using the volume of fluid and realizable k-ε models. The results indicate that the inception point location moves downwards with the increase of the discharge of the stepped spillways. The length of the non-aerated flow zone increases with the discharge. The inception point location moves downwards as the step height decreases and the step number increases at the same discharge. The inception point location of the round stepped spillway model is much closer to the spillway crest than that of the flat stepped spillway with the same number of steps. The inception point location of the pooled stepped spillway is closer to the spillway crest than that of the flat stepped spillway, but more downstream than that of the round stepped spillway.

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Section: LImentioning

confidence: 99%

Effect of Height and Geometry of Stepped Spillway on Inception Point Location

2019

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“…2.5 2.5 2.5 2.5 Aeration Aeration Aeration Aeration e e e efficiency fficiency fficiency fficiency e e e equation quation quation quation Aeration performance depends on the initial dissolved oxygen (DO) level, required discharge dissolved , , 1 1 (11) Where La = L -Le is the aerated length; Le is the inception length of [17] given on Table 2, the constants a1, a2, a3, a4 are determined experimentally, Table 3 showed the values of the discharge and the head data, the log of the parameters were plotted on Microsoft excel 2003 (Fig.5) to determine k=0.33 and n=1.5 of Equation (6), which is the flow model employed to run the aeration experiment. For every model, at a given unit discharge and at the standard temperature of 20 o C, the aeration parameters in Equation (11) were determined and plotted, as can be viewed in Figures 6a-8c.…”

Section: Determination Ofmentioning

confidence: 99%

“…From the studies of self aerated spillway flows, [15] concluded that the turbulent boundary layer or development length, caused by the stepped chute, initiated air entrainment when its thickness is approximately the depth of flow. A feasible equation was presented by [16] which overestimated the development length and was modified by [17]; for optimization purpose. This research used the modified inception length of [17] in order to determine the aerated length in this study.…”

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confidence: 99%

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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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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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“…Although an unstructured grid needs more time and memory to solve the problem, it is still worth it to use in the study. The unstructured grid for this research was developed in Gambit software by triangular elements [29][30] [31].…”

Section: Geometry and Meshingmentioning

confidence: 99%

Energy Loss Estimation and Flow Simulation in the skimming flow Regime of Stepped Spillways with Inclined Steps and End Sill: A Numerical Model

Hamedi¹,

Ketabdar²

2016

IJSEA

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Abstract:Energy dissipaters in dams consider as expensive structures; therefore, economic design of these structure are desirable.Stepped spillways can be use as energy dissipater to reduce the size and cost of the stilling basin. Hard experimental works, high-cost and time-consuming laboratory methods brought about some difficulties to determine the most-efficient design of the steps. This research deals with comparing the two-dimensional numerical simulation and experimental description in stepped spillways equipped with inclined steps and end sill together and presents a quick, trustworthy, economical, and numerical approach to designing the steps. In complicated geometries, simulation is more problematic than simulation of flow in horizontal steps, because it needs more precision around the end sills. Finite volume method and the k-ε standard model are proposed to simulate the flow pattern and evaluate the energy loss over stepped spillway. The flow pattern and velocity vectors resulted from numerical simulation is in a good agreement with the experimental results. Also, energy losses resulted from the numerical approach have been compared with laboratory measurements and demonstrate reasonable agreement.

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Study of the Inception Length of Flow over Stepped Spillway Models

Cited by 6 publications

References 7 publications

Effect of Height and Geometry of Stepped Spillway on Inception Point Location

Effect of Height and Geometry of Stepped Spillway on Inception Point Location

Empirical Modeling of Oxygen Uptake of Flow Over Stepped Chutes

Energy Loss Estimation and Flow Simulation in the skimming flow Regime of Stepped Spillways with Inclined Steps and End Sill: A Numerical Model

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