scholarly journals IMPROVEMENT OF THE HYDRAULIC JUMP FEATURES USING INCOMPLETE CIRCULAR PILES

2020 ◽  
Vol 4 (1) ◽  
pp. 19-22
Author(s):  
Nassar M.A
Keyword(s):  
Hydraulic Jump ◽  
Roughness Elements ◽  
Stilling Basins

The roughness elements are efficient tools to control the features of the hydraulic jump in the rectangular stilling basins. The present study suggests the use of modified elements to control the features of the free jump. The proposed tool is an incomplete circular pile. The use of piles in a one row with the different setup has been investigated. The measurements showed that the case of piles with the comparative summation areas A/∆=6.72 and the comparative distances between piles X/H1 =0.0 reduced the comparative height and length of the free jump by 11% and 24.6%, respectively. The paper detected the necessary helpful statistical formulas for the phenomenon.

scholarly journals Experimental Characterization of the Hydraulic Jump Profile and Velocity Distribution in a Stilling Basin Physical Model

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1758
Author(s):  
Juan Macián-Pérez ◽  
Francisco Vallés-Morán ◽  
Santiago Sánchez-Gómez ◽  
Marco De-Rossi-Estrada ◽  
Rafael García-Bartual
Keyword(s):  
Free Surface ◽  
Energy Dissipation ◽  
Velocity Distribution ◽  
Physical Model ◽  
Hydraulic Jump ◽  
Surface Profile ◽  
Air Entrainment ◽  
Stilling Basin ◽  
Free Surface Profile ◽  
Stilling Basins

The study of the hydraulic jump developed in stilling basins is complex to a high degree due to the intense velocity and pressure fluctuations and the significant air entrainment. It is this complexity, bound to the practical interest in stilling basins for energy dissipation purposes, which brings the importance of physical modeling into the spotlight. However, despite the importance of stilling basins in engineering, bibliographic studies have traditionally focused on the classical hydraulic jump. Therefore, the objective of this research was to study the characteristics of the hydraulic jump in a typified USBR II stilling basin, through a physical model. The free surface profile and the velocity distribution of the hydraulic jump developed within this structure were analyzed in the model. To this end, an experimental campaign was carried out, assessing the performance of both, innovative techniques such as the time-of-flight camera and traditional instrumentation like the Pitot tube. The results showed a satisfactory representation of the free surface profile and the velocity distribution, despite some discussed limitations. Furthermore, the instrumentation employed revealed the important influence of the energy dissipation devices on the flow properties. In particular, relevant differences were found for the hydraulic jump shape and the maximum velocity positions within the measured vertical profiles, when compared to classical hydraulic jumps.

scholarly journals Analysis of the Flow in a Typified USBR II Stilling Basin through a Numerical and Physical Modeling Approach

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 227 ◽  
Author(s):  
Juan Francisco Macián-Pérez ◽  
Rafael García-Bartual ◽  
Boris Huber ◽  
Arnau Bayon ◽  
Francisco José Vallés-Morán
Keyword(s):  
Physical Model ◽  
Hydraulic Jump ◽  
Numerical Approach ◽  
Free Surface Flows ◽  
United States Bureau ◽  
Bureau Of Reclamation ◽  
Stilling Basin ◽  
Modeling Approach ◽  
Stilling Basins ◽  
Energy Dissipation Devices

Adaptation of stilling basins to higher discharges than those considered for their design implies deep knowledge of the flow developed in these structures. To this end, the hydraulic jump occurring in a typified United States Bureau of Reclamation Type II (USBR II) stilling basin was analyzed using a numerical and experimental modeling approach. A reduced-scale physical model to conduct an experimental campaign was built and a numerical computational fluid dynamics (CFD) model was prepared to carry out the corresponding simulations. Both models were able to successfully reproduce the case study in terms of hydraulic jump shape, velocity profiles, and pressure distributions. The analysis revealed not only similarities to the flow in classical hydraulic jumps but also the influence of the energy dissipation devices existing in the stilling basin, all in good agreement with bibliographical information, despite some slight differences. Furthermore, the void fraction distribution was analyzed, showing satisfactory performance of the physical model, although the numerical approach presented some limitations to adequately represent the flow aeration mechanisms, which are discussed herein. Overall, the presented modeling approach can be considered as a useful tool to address the analysis of free surface flows occurring in stilling basins.

Energy Dissipation in Culverts by Forced Hydraulic Jump within a Barrel

2005 ◽  
Vol 1904 (1) ◽  
pp. 124-132
Author(s):  
Rollin H. Hotchkiss ◽  
Emily A. Larson ◽  
David M. Admiraal
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Design Procedure ◽  
High Energy ◽  
Easy Access ◽  
Flow Energy ◽  
Energy Flows ◽  
Stilling Basins ◽  
Maintenance Activities ◽  
Drop Structure

Riprap and concrete stilling basins are often built at culvert outlets to keep high-energy flows from scouring the streambed. Two simple alternatives to large basins are examined: a horizontal apron with an end weir and a drop structure with an end weir. The two designs are intended to reduce the flow energy at the outlet by inducing a hydraulic jump within the culvert barrel without the aid of tailwater. This research examines the jump geometry and the effectiveness of each jump type and proposes a design procedure for practicing engineers. The design procedure is applicable to culverts with approach Froude numbers from 2.6 to 6.0. Both designs are effective in reducing outlet velocity 0.7 to 8.5 ft/s (0.21 to 2.59 m/s), momentum 10% to 48%, and energy 6% to 71%. The design layouts allow easy access for maintenance activities.

Prediction of pressure fluctuations on sloping stilling basins

2006 ◽  
Vol 33 (11) ◽  
pp. 1379-1388 ◽  
Author(s):  
A Güven ◽  
M Günal ◽  
A Çevik
Keyword(s):  
Neural Network ◽  
Pressure Fluctuation ◽  
Hydraulic Jump ◽  
Regression Models ◽  
Pressure Fluctuations ◽  
Network Models ◽  
Neural Network Models ◽  
Mean Pressure ◽  
Stilling Basins ◽  
The Mean

Various types of hydraulic jump occurring on horizontal and sloping channels have been analyzed experimentally, theoretically, and numerically and the results are available in the literature. In this study, artificial neural network models were developed to simulate the mean pressure fluctuations beneath a hydraulic jump occurring on sloping stilling basins. Multilayers feed a forward neural network with a back-propagation learning algorithm to model the pressure fluctuations beneath such a type of hydraulic jump (B-jump). An explicit formula that predicts the mean pressure fluctuation in terms of the characteristics that contribute most to the hydraulic jump occurring on the sloping basins is presented. The proposed neural network models are compared with linear and nonlinear regression models that were developed using considered physical parameters. The results of the neural network modelling are found to be superior to the regression models and are in good agreement with the experimental results due to relatively small values of error (mean absolute percentage error).Key words: neural networks, pressure fluctuation, hydraulic jump, sloping stilling basin, explicit NN formulation, regression analysis.

Numerical computation of the flow in hydraulic jump stilling basins

2008 ◽  
Vol 46 (6) ◽  
pp. 739-752 ◽  
Author(s):  
R.F. Carvalho ◽  
C.M. Lemos ◽  
C.M. Ramos
Keyword(s):  
Numerical Computation ◽  
Hydraulic Jump ◽  
Stilling Basins

Radial flow stilling basins with baffle blocks

1989 ◽  
Vol 16 (4) ◽  
pp. 489-497 ◽  
Author(s):  
Peter C. Nettleton ◽  
John A. McCorquodale
Keyword(s):  
Key Words ◽  
Hydraulic Jump ◽  
Water Surface ◽  
Radial Flow ◽  
Surface Profile ◽  
Hydraulic Jumps ◽  
Bureau Of Reclamation ◽  
Stilling Basin ◽  
Jump Length ◽  
Stilling Basins

A total of 120 tests of forced radial flow hydraulic jumps have been analyzed in order to develop curves and equations for the design of radial stilling basins. The jump depth, the water surface profile, wave amplitudes, the allowable flare angle, and the jump length are defined in terms of entrance conditions, the baffle position, and the baffle height. An example design is given and compared with a USBR (U.S. Bureau of Reclamation) Type III stilling basin. Key words: forced hydraulic jump, radial flow, design, stilling basins, baffles, radial hydraulic jump, circular hydraulic jump.

scholarly journals Pressure Fluctuations in the Spatial Hydraulic Jump in Stilling Basins with Different Expansion Ratio

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 60
Author(s):  
Nasrin Hassanpour ◽  
Ali Hosseinzadeh Dalir ◽  
Arnau Bayon ◽  
Milad Abdollahpour
Keyword(s):  
Hydraulic Jump ◽  
Laboratory Tests ◽  
Pressure Fluctuations ◽  
Expansion Ratio ◽  
Hydraulic Jumps ◽  
Extreme Pressure ◽  
Flow Conditions ◽  
Stilling Basins ◽  
Channel Expansion ◽  
Shed Light

Pressure fluctuations are a key issue in hydraulic engineering. However, despite the large number of studies on the topic, their role in spatial hydraulic jumps is not yet fully understood. The results herein shed light on the formation of eddies and the derived pressure fluctuations in stilling basins with different expansion ratios. Laboratory tests are conducted in a horizontal rectangular flume with 0.5 m width and 10 m length. The range of approaching Froude numbers spans from 6.4 to 12.5 and the channel expansion ratios are 0.4, 0.6, 0.8, and 1. The effects of approaching flow conditions and expansion ratios are thoroughly analyzed, focusing on the dimensionless standard deviation of pressure fluctuations and extreme pressure fluctuations. The results reveal that these variables show a clear dependence on the Froude number and the distance to the hydraulic jump toe. The maximum values of extreme pressure fluctuations occur in the range 0.609<X<3.385, where X is dimensionless distance from the toe of the hydraulic jump, which makes it highly advisable to reinforce the bed of stilling basins within this range.

scholarly journals The Effects of Different Shaped Baffle Blocks on the Energy Dissipation

2020 ◽  
Vol 6 (5) ◽  
pp. 961-973
Author(s):  
Nassrin Jassim Hussien Al-Mansori ◽  
Thair Jabbar Mizhir Alfatlawi ◽  
Khalid S. Hashim ◽  
Laith S. Al-Zubaidi
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Concrete Block ◽  
Naval Research ◽  
Irrigation Systems ◽  
Force Ratio ◽  
Stilling Basins ◽  
Baffle Block ◽  
Length Reduction ◽  
Better Than

Stilling basins can be defined as energy dissipaters constructed of the irrigation systems. This study aims at investigating the performance of the new seven baffle blocks design in terms of reducing the dimensions of stilling basins in irrigation systems. In order to assess the hydraulic efficiency of a new model for baffle block used in stilling basins, a Naval Research Laboratory (NRL) has conducted. The results of this study demonstrate that the performance of the new baffle block, in term of hydraulic jump length reduction and hydraulic energy dissipation, it's better than standard blocks. However, the ratios of the drag resistance attributed to the new baffles block (FB / F2) have been larger than that applied on the normal block. It was found that the new block dissipates the energy by 9.31% more than the concrete block, and decreases the length of the hydraulic jump by 38.6% in comparison with the standard blocks. However, the new block maximizes the drag force ratio by 98.6% in comparison with the standard baffle blocks. The findings indicated that in terms of energy reduction and dissipation in the length of the hydraulic jump, the new block is superior to the other kinds.

Laboratory study of stilling basin using trapezoidal bed elements

2020 ◽  
Vol 29 (4) ◽  
pp. 409-420
Author(s):  
Thair Al-Fatlawi ◽  
Nassrin Al-Mansori ◽  
Nariman Othman
Keyword(s):  
Energy Dissipation ◽  
Laboratory Study ◽  
Hydraulic Jump ◽  
Stilling Basin ◽  
Smooth Model ◽  
Stilling Basins ◽  
Spillway Structures ◽  
Baffle Block ◽  
Pressure Driven

When designing dam spillway structures, the most significant consideration is the energy dissipation arrangements. Different varieties of baffle blocks and stilling basins have been used in this context. However, the hydraulic jump form of stilling basin is considered to be the most suitable. The main objective of this research was to introduce four different baffle block shapes (models arranged from A to D, installed at slopes 0.00, 0.04, 0.06 and 0.08 in the stilling basins). To illustrate the consequences for the qualities of pressure-driven bounce, each model was attempted in the bowl. The trials applied Froude numbers between 6.5 and 9.2. The puzzle square model D provided the best outcomes compared to the models A, B, C and smooth. Model D with different models at inclines 0.00, 0.04, 0.06 and 0.08 was used to consider the impacts of perplex hinders on water driven-bounce when bed slants were changed. When the model D baffle used instead of a smooth bed at 0.08 slope, the reduction in y2 / y1 reached 12.8%, and Lj / y1 was 18.9%. Among the different bed slopes, a normal decrease in y2 / y1 ranged from approximately 10.3%, whereas the normal decrease in Lj / y1 was about 13.8% when the model D baffle was used instead of the model A baffle with a horizontal slope bed of 0.00. The results show that the new shapes led to a decrease in sequent profundity proportion and length of jump proportion; however, the energy dissipation proportion increased.

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