Flip Bucket without and with Deflectors

Juon, Roman; Hager, Willi H.

doi:10.1061/(asce)0733-9429(2000)126:11(837)

Cited by 65 publications

(43 citation statements)

References 7 publications

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“…This effect mainly concerns the part beyond the 90% air concentrations, which is irrelevant to define the jet surface. Heller et al (2005) identified scale effects regarding the jet trajectories for h o ≤ 0.04 m, whereas Juon and Hager (2000) report of h o ≤ 0.05 m.…”

Section: Scale Effectsmentioning

confidence: 99%

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Trajectories and air flow features of ski jump-generated jets

Pfister

Hager

Boes

2014

Journal of Hydraulic Research

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Ski jumps are frequently applied as spillways of high dams. The resulting jet impact location on the plunge pool surface is often distant from the dam toe so that the latter is protected from scouring. Furthermore, the jet disintegrates and disperses prior to its impact, thereby reducing the specific energy addition to the plunge pool. The present research addresses four aspects, based on three physical modelling campaigns: (1) geometry of upper and lower jet trajectories; (2) virtual jet take-off angles for the trajectory computations; (3) average and minimum cross-sectional air concentrations along the jet; and (4) general jet air concentration profiles. It is shown that the trajectory parabola may also be applied for negative jet take-off angles, and that these are smaller than the bucket angle. As for the air concentration distribution along the jet, tests indicate that the latter depends exclusively on the relative jet black-water core length.

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Section: Scale Effectsmentioning

confidence: 99%

“…Recent works on ski jumps include those of Juon and Hager (2000) with a literature review on past studies, and a preliminary physical model investigation on the plane and spatial features of ski jump jets. Heller et al (2005) considered the two-dimensional ski jump trajectories, again based on physical modelling.…”

Section: Introductionmentioning

confidence: 99%

Trajectories and air flow features of ski jump-generated jets

Pfister

Hager

Boes

2014

Journal of Hydraulic Research

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“…The tests involved a large-scale model, as recommended by Toombes and Chanson (2007). Scale effects relative to jet trajectories were discussed by Juon and Hager (2000) and Heller et al (2005), recommending for water jets in the atmosphere h o ≥ 0.05 m and h o ≥ 0.04 m, respectively. As a consequence, the primary jet disintegration, i.e.…”

Section: Scale Effectsmentioning

confidence: 99%

Deflector-jets affected by pre-aerated approach flow

Pfister

Hager

2012

Journal of Hydraulic Research

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Jets generated at chute ends move a potential scour zone away from the dam, and dissipate flow energy to reduce the scour. Usually, so-called flip buckets or ski jumps are provided to generate jets, yet they are rarely issued by deflectors. The application of a theoretical mass point parabola is limited to predict the jet features, because effects related to the take-off angle and the disintegration process affect the jet air transport and trajectories. This research discusses the effect of pre-aeration of the approach chute flow on the jet features. A comparison with a former study indicates that mainly the upper jet portion is affected, that the black water jet core becomes shorter, and that the air transport increases. Although the lower trajectory is less affected and thus remains more coherent, the small effect of pre-aeration is sufficient to reduce the total jet throw length, so that pre-aerated jets tend to be shorter as compared with black-water approach flow jets, in agreement with prototype observations.

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“…Juan and Hager [2] experimentally investigated the e ect of Froude number and bucket geometry on dynamic pressure distribution for circular ip buckets and compared the results with theoretical equations. Heller et al [3] extended Juan and Hager's [2] circular ip buckets experiments in order to study pressure distribution at the bottom of bucket, ow characteristics for di erent geometries, and Froude numbers. Their attempts resulted in providing equations for calculation of value and location of maximum pressure.…”

Section: Introductionmentioning

confidence: 99%

The objective design of triangular bucket for dam's spillway using Non-dominated Sorting Genetic Algorithm II: NSGA-II

Hojjati

Neyshabouri

2017

Scientia Iranica

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Abstract. Ski jump is one of the most e ective structures in energy dissipation over spillways. Spillways have long been of practical importance to safety of dams. The major criteria in hydraulic design are based on the analytical and empirical methods. In the current study, in order to increase chute spillway e ciency, a multi-objective evolutionary algorithm known as the Non-dominated Sorting Genetic Algorithm II (NSGA-II) has been utilized to design the optimal triangular bucket angle and chute width. In design method, two separate objective functions have been used. In the rst objective function, equations of dynamic pressure of the bucket, the jet length after bucket, and the scour depth have been used. The second objective function is related to construction volume of chute spillway. For calibrating the rst objective function, characteristics of Karoon III dam have been used as a case study. The di erence between design parameters of Karoon III spillway and those from NSGA-II algorithm method is less than 12 percent. According to the results, if the jet length is considered as the most impressive parameter in the rst objective function, design of the spillway becomes frugal.

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Flip Bucket without and with Deflectors

Cited by 65 publications

References 7 publications

Trajectories and air flow features of ski jump-generated jets

Trajectories and air flow features of ski jump-generated jets

Deflector-jets affected by pre-aerated approach flow

The objective design of triangular bucket for dam's spillway using Non-dominated Sorting Genetic Algorithm II: NSGA-II

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