Longitudinal distribution of extreme pressures in a hydraulic jump downstream of a stepped spillway

ABSTRACT The overflow system of a dam safely controls the water level of a reservoir. The design of these structures should predict the damage caused by the action of the turbulent flow to which they are subject to. The combination formed by a stepped spillway followed by a stilling basin promotes a considerable portion of the energy dissipation in the actual chute of the stepped spillway but it is not sufficient to completely avoid the risk of damaging the basin. In this paper, we analyze the longitudinal distribution of extreme pressures in a stilling basin downstream of a stepped spillway. The study was based on the instant pressure data from the tests carried out in a physical model in the Laboratório de Obras Hidráulicas in IPH/UFRGS. Thus, it was found that the pressure behavior is similar to that observed in studies involving smooth chute spillways, except in the area surrounding the base of the stepped spillway, where high pressure fluctuations may occur. This happens as a result of the impact caused by the flow in the dissipation structure, which is not observed downstream of smooth chute spillways due to the existence of a vertical concordance curve between the spillway and the stilling basin.

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Macro-turbulent characteristcs of pressures in hydraulic jump formed downstream of a stepped spillway

RBRH ◽

10.1590/2318-0331.011716034 ◽

2017 ◽

Vol 22 (0) ◽

Cited By ~ 1

Author(s):

Carolina Kuhn Novakoski ◽

◽

Eliane Conterato ◽

Marcelo Marques ◽

Eder Daniel Teixeira ◽

...

Keyword(s):

Pressure Fluctuation ◽

Hydraulic Jump ◽

Pressure Fluctuations ◽

Longitudinal Distribution ◽

Stepped Spillway ◽

Stepped Spillways ◽

Stilling Basin ◽

Large Pressure ◽

Skewness Coefficient ◽

Mean Pressure

ABSTRACT Stilling basins are structures built at the base of the spillway to dissipate energy, by means of a hydraulic jump. Hydraulic jump is a turbulent phenomenon that causes large pressure fluctuation in the stilling basin bottom, and can damage the sink structure through mechanisms such as fatigue, upflit pressure and cavitation. The use of stepped spillways allows the dissipation of a parcel of the energy while the water falls by the spillway, allowing a reduction in the stilling basin’s dimensions and cost. The present article presents the analysis of the longitudinal distribution of mean pressure, pressure fluctuations, skewness coefficient and kurtosis coefficient, derived from tests on physical hydraulic models. Pressure values measured in a stilling basin downstream of a stepped spillway (for Froude numbers between 5 and 8) were compared with data observed in a stilling basin downstream of a smooth spillway with a radius of concordance between the chute and the basin (for Froude numbers between 4.5 and 10). The results of these studies show that the mean pressures and the pressure fluctuation observed in the stilling basin downstream of stepped spillway present maximum values at the spillway’s closest point, differing, thus, from those at the smooth spillway. The longitudinal distribution of skewness and kurtosis coefficients enabled to define the positions for flow detachment start, roller ending and as well as the ending of the influence of the hydraulic jump over the flow.

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The impact of deepening the stilling basin on the characteristics of hydraulic jump

Czasopismo Techniczne ◽

10.4467/2353737xct.18.046.8341 ◽

2018 ◽

Keyword(s):

Hydraulic Jump ◽

Stilling Basin ◽

The Impact

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ESTIMATION OF HYDRAULIC JUMP CHARACTERISTICS IN STILLING BASIN WITH GUIDE WALLS

JES. Journal of Engineering Sciences ◽

10.21608/jesaun.2012.114531 ◽

2012 ◽

Vol 40 (6) ◽

pp. 1599-1609

Author(s):

Habib A.A. ◽

Abdel-Azim M. Ali ◽

Abd-Allh Y.M ◽

Saleh y.k.

Keyword(s):

Hydraulic Jump ◽

Stilling Basin

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Multiple orifices in customized microsystem high-pressure emulsification: The impact of design and counter pressure on homogenization efficiency

Chemical Engineering Journal ◽

10.1016/j.cej.2013.12.105 ◽

2014 ◽

Vol 248 ◽

pp. 107-121 ◽

Cited By ~ 26

Author(s):

Jan Henrik Finke ◽

Svea Niemann ◽

Claudia Richter ◽

Thomas Gothsch ◽

Arno Kwade ◽

...

Keyword(s):

High Pressure ◽

Counter Pressure ◽

The Impact

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Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽

10.3390/cryst11040378 ◽

2021 ◽

Vol 11 (4) ◽

pp. 378

Author(s):

Li Zhao ◽

Zhiwei Hu ◽

Hanjie Guo ◽

Christoph Geibel ◽

Hong-Ji Lin ◽

...

Keyword(s):

High Pressure ◽

Magnetic Properties ◽

Magnetic Susceptibility ◽

Crystal Growth ◽

Physical Properties ◽

Single Crystal ◽

Single Crystals ◽

Magnetic Moments ◽

Single Crystal Growth ◽

The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

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Missed Shots at the Free-Throw Line

Journal of Sports Economics ◽

10.1177/1527002515593779 ◽

2015 ◽

Vol 18 (6) ◽

pp. 539-559 ◽

Cited By ~ 16

Author(s):

Mattie Toma

Keyword(s):

High Pressure ◽

National Collegiate Athletic Association ◽

Statistical Significance ◽

National Basketball Association ◽

Choking Under Pressure ◽

Professional Basketball ◽

Free Throw ◽

Percentage Points ◽

Male College ◽

The Impact

Choking under pressure represents a phenomenon in which individuals faced with a high-pressure situation do not perform as well as would be expected were they performing under normal conditions. In this article, I identify determinants that predict a basketball player’s susceptibility to choking under pressure. Identification of these determinants adds to our understanding of players’ psychology at pivotal points in the game. My analysis draws on play-by-play data from ESPN.com that feature over 2 million free-throw attempts in women’s and men’s college and professional basketball games from the 2002-2013 seasons. Using regression analysis, I explore the impact of both gender and level of professionalism on performance in high-pressure situations. I find that in the final 30 seconds of a tight game, Women’s National Basketball Association and National Basketball Association players are 5.81 and 3.11 percentage points, respectively, less likely to make a free throw, while female and male college players are 2.25 and 2.09 percentage points, respectively, less likely to make a free throw, though statistical significance cannot be established among National Collegiate Athletic Association women. The discrepancy in choking between college and professional players is pronounced when comparing male college players who do and do not make it to the professional level; the free-throw performance of those destined to go pro falls 6 percentage points more in high-pressure situations. Finally, I find that women and men do not differ significantly in their propensity to choke.

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The Inductive Coil Technique for High-Pressure Measurements: An Analysis of Nonhomogeneous Material Environment as a Source of Irreproducibility and Error

Journal of Basic Engineering ◽

10.1115/1.3609657 ◽

1967 ◽

Vol 89 (3) ◽

pp. 554-560 ◽

Cited By ~ 4

Author(s):

A. A. Giardini

Keyword(s):

High Pressure ◽

Internal Pressure ◽

Elastic Constants ◽

Graphical Form ◽

Pressure Measurements ◽

Pressure Data ◽

Nonhomogeneous Material ◽

Resistivity Measurements ◽

Material Environment ◽

Critical Yield

Significant sources of error independent of the apparatus are analyzed on the basis of experimental experience and elastic theory. All are mechanical in nature and subject to corrective action. The most serious is found to be self-generating internal pressure differences which result from differential elastic and dimensional values in multicomponent assemblies. High-pressure data on elastic constants, relative critical yield stresses, radial displacements, and ratios of external to internal pressure for various compositional arrangements of pyrophyllite, MgO, NaCl, and AgCl are given in graphical form. Observance of suggested corrective measures can render the inductive coil technique capable of operational accuracies of 2 percent or better in compressibility and resistivity measurements.

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Effect of ball collision direction on a wet mechanochemical reaction

Scientific Reports ◽

10.1038/s41598-020-80342-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Takahiro Kozawa ◽

Kayo Fukuyama ◽

Kizuku Kushimoto ◽

Shingo Ishihara ◽

Junya Kano ◽

...

Keyword(s):

High Pressure ◽

High Temperature ◽

Reaction Rates ◽

Tangential Component ◽

Normal Direction ◽

Mechanochemical Reaction ◽

Precipitation Mechanism ◽

The Impact ◽

Mechanochemical Reactions ◽

Ball Motion

AbstractMechanochemical reactions can be induced in a solution by the collision of balls to produce high-temperature and high-pressure zones, with the reactions occurring through a dissolution–precipitation mechanism due to a change in solubility. However, only a fraction of the impact energy contributes to the mechanochemical reactions, while the rest is mainly consumed by the wear of balls and the heat generation. To clarify whether the normal or tangential component of collisions makes a larger contribution on the reaction, herein we studied the effect of collision direction on a wet mechanochemical reaction through combined analysis of the experimental reaction rates and simulated ball motion. Collisions of balls in the normal direction were found to contribute strongly to the wet mechanochemical reaction. These results could be used to improve the synthesis efficiency, predict the reaction, and lower the wear in the wet mechanochemical reactions.

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