scholarly journals Hydraulic model experiment of energy dissipation on the horizontal and USBR II stilling basin

2021 ◽  
Vol 930 (1) ◽  
pp. 012029
Author(s):  
V Dermawan ◽  
Suhardjono ◽  
L Prasetyorini ◽  
S Anam
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Control Point ◽  
Hydraulic Model ◽  
Flow Depth ◽  
Flow Conditions ◽  
Depth Measurement ◽  
Stilling Basin ◽  
Flow Energy ◽  
Starting Point

Abstract Flow conditions on overflow systems can result in construction failure, mainly due to the high flow energy. Stilling basin at downstream of the spillway is useful for reducing flow energy. It can reduce the destructive force of water flow. Controlling the hydraulic jump is an important part that includes the jump’s energy, length, and height. The physical hydraulic model was carried out with several series, by making a series of bottom lowering of horizontal and USBR II stilling basin. The experimental study is expected to represent flow behavior in the overflow system regarding flow conditions and energy dissipation. Based on the analytical calculation of flow velocity, the amount of flow energy that occurs at each control point is calculated. The control points are the starting point of the spillway, the chute way toe, and flow depth after the hydraulic jump. The energy loss can be calculated for each control point, while the efficiency of energy dissipation on stilling basin is calculated at the downstream flow depth after the hydraulic jump. Velocity calculated by dividing discharge per unit width by water depth which is based on the flow depth measurement data in the hydraulic model.

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 Uniform flow and energy dissipation of hydraulic-jump-stepped spillways

2020 ◽  
Vol 20 (4) ◽  
pp. 1546-1553
Author(s):  
Yu Zhou ◽  
Jianhua Wu ◽  
Fei Ma ◽  
Jianyong Hu
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Hydraulic Jump ◽  
Flow Region ◽  
Uniform Flow ◽  
Stepped Spillway ◽  
Flow Depth ◽  
Clear Water ◽  
Air Concentration ◽  
Stepped Spillways

Abstract In skimming flow, a uniform flow can be achieved and the flow depth, velocity and air concentration remain constant if a stepped spillway is sufficiently long. In this study, physical model experiments were performed to investigate the uniform characteristics and energy dissipation of a hydraulic-jump-stepped spillway, which is a new type of stepped spillway for increasing the unit discharge capacity and energy dissipation. Based on the redefinition of uniform flow, experimental results show that at a given stepped spillway slope, a smaller height for the beginning of the uniform flow region, a greater uniform aerated flow depth and a greater uniform equivalent clear water flow depth can be obtained as compared with the traditional stepped spillway due to strong aeration in the aeration basin. Under the condition of uniform flow, the energy dissipation rate of stepped spillways can be estimated by the equivalent clear water flow depth with given inflow conditions. Compared with the traditional stepped spillway, the uniform flow over the hydraulic-jump-stepped spillway has a smaller specific energy, revealing that the hydraulic-jump-stepped spillway is more advantageous for dissipating energy, especially at large unit discharges.

scholarly journals Study on the Best Depth of Stilling Basin with Shallow-Water Cushion

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1801
Author(s):  
Qiulin Li ◽  
Lianxia Li ◽  
Huasheng Liao
Keyword(s):  
Energy Dissipation ◽  
Shallow Water ◽  
Froude Number ◽  
Flow Regime ◽  
Dissipation Rate ◽  
Hydraulic Jump ◽  
Energy Dissipation Rate ◽  
Main Stream ◽  
Stilling Basin ◽  
Key Factor

The depth of the stilling basin with shallow-water cushion (SBSWC) is a key factor that affects the flow regime of hydraulic jump in the basin. However, the specific depth at which the water cushion is considered as ‘shallow’ has not been stated clearly by far, and only conceptual description is provided. Therefore, in order to define the best depth of SBSWC and its relationship between the Froude number at the inlet of the stilling basin, a large number of experiments were carried out to investigate SBSWC. First of all, 30 cases including five different Froude numbers and six depths were selected for which large eddy simulation (LES) was firstly verified by the experiments and then adopted to calculate the hydraulic characteristics in the stilling basin. Finally, three standards, based on the flow regime of hydraulic jump, the location of the main stream and the energy dissipation rate, were proposed to define the best depth of SBSWC. The three criteria are as follows: (1) a complete hydraulic jump occurs in the basin (2) the water cushion is about 1/10–1/3 deep of the stilling basin, and (3) the energy dissipation rate is more than 70% and the unit volume energy dissipation rate is as high as possible. It showed that the best depth ratio of SBSWC (depth to length ratio) was between 0.1 and 0.3 and it also indicated the best depth increased with the increase in Froude number. The results of the work are of significance to the design and optimizing of SBSWC.

scholarly journals Experimental Analysis of Hydraulic Jump at High Froude Numbers

2021 ◽  
Author(s):  
Oguz Simsek ◽  
Mevlut Sami Akoz ◽  
Nazire Goksu Soydan Oksal
Keyword(s):  
Turbulence Intensity ◽  
Hydraulic Jump ◽  
Laser Doppler Anemometry ◽  
Relative Height ◽  
Flow Conditions ◽  
Structural Configuration ◽  
Stilling Basin ◽  
Rapid Transition ◽  
Sill Height ◽  
Energy Dissipation Ratio

Abstract The hydraulic jump is a rapid transition state from supercritical to subcritical flow that occurs commonly in rivers, prismatic channels and downstream of spillways. In this study, the characteristics of the hydraulic jump in a stilling basin downstream of the spillway chute channel with the slopes of α = 12o and 30o were investigated experimentally for different Froude numbers of incoming flow, Fr1 = 7, 7.5, 8, 9, 10 and 12, and relative heights of sill in the range of 4 < hs/h1 (S) < 13 (S relative height). In the experiments, in which velocity field measured by laser Doppler Anemometry, it was particularly focused on the effects of both different structural configuration and flow conditions on the hydraulic jump and energy dissipation ratio. Experimental measurements showed that the length of hydraulic jump and the roller zone increases with the decrease of the sill height for α = 12o and 30o. In addition, the length of the hydraulic jump and roller zone increased with decreasing Froude numbers. The turbulence intensity in the jump region was determined to be greater than the turbulence intensity in the region near the bottom of stilling basin. The turbulence intensity, in general, tended to decrease with decreasing Froude number.

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.

Energy dissipation by vertically placed screens

2007 ◽  
Vol 34 (4) ◽  
pp. 557-564 ◽  
Author(s):  
Zafer Bozkus ◽  
Pinar Çakir ◽  
A Metin Ger
Keyword(s):  
Energy Dissipation ◽  
Froude Number ◽  
Hydraulic Jump ◽  
Large Range ◽  
Hydraulic Structure ◽  
Flow Depth ◽  
Supercritical Flow ◽  
Series Of Experiments ◽  
Upstream Flow

Screens can be utilized efficiently for dissipating energy of water. In this study, water flowing beneath a gate is used to simulate the flow downstream of a small hydraulic structure, and vertically placed screens are used as an alternative tool for energy dissipation. Investigations are conducted using a series of experiments. The porosity, thickness, and location of the screens are the major parameters together with the Froude number of the upstream flow. The experiments cover a range of supercritical Froude numbers between 5.0 and 18.0, porosities between 20% and 60%, and screen locations up to 100 times the undisturbed upstream flow depth. The thicknesses of the screens used are in the order of the undisturbed upstream flow depth. The results show the importance of each parameter in the energy-dissipating performance of the screens and the system. It is observed that screens dissipate significantly more energy than a conventional hydraulic jump within the large range of Froude numbers covered in the study. The results are also in agreement with the results of an earlier similar study.Key words: screen, energy dissipation, hydraulic jump, porosity, supercritical flow.

scholarly journals Hydraulic Model Investigation on Stepped Spillway's Plain and Slotted Roller Bucket

2019 ◽  
Vol 9 (4) ◽  
pp. 4419-4422
Author(s):  
A. S. Kote ◽  
P. B. Nangare
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Hydraulic Model ◽  
Physical Models ◽  
Stepped Spillway ◽  
Stilling Basin ◽  
Discharge Water ◽  
Energy Dissipater ◽  
Low Head ◽  
High Head

In ogee spillway, the released flood water from crest to toe possesses a high amount of kinetic energy causing scour and erosion on the spillway structure. The dam projects normally have a stilling basin as an energy dissipater which has specific energy dissipation limitations. The stepped spillway is a better option to minimize kinetic energy along the chute and safely discharge water in the river domain. The Khadakwasla dam is situated in Pune, Maharashtra (India), and has scouring and erosion issues on the chute of ogee spillway and on the stilling basin. The present study develops a physical hydraulic model for the dam spillway with steps, plain and slotted roller bucket as per IS Code 6934 (1998) and IS Code 7365 (2010). Experiments were performed at heads of 4m (low head) and 6m (high head) on the developed physical models, namely on the plain and slotted roller bucket model for the ogee spillway and the plain and slotted roller bucket model for the stepped spillway. It was found that the plain roller bucket of ogee spillway dissipates 81.26% of energy at the low head, whereas the stepped spillway with slotted roller bucket dissipates the 83.86% of the energy at the high head.

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.

Energy dissipation in a deep tailwater stilling basin with partial flaring gate piers

2020 ◽  
Vol 47 (5) ◽  
pp. 523-533
Author(s):  
Zhao Zhou ◽  
Junxing Wang ◽  
David Z. Zhu
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Hydraulic Jump ◽  
High Speed ◽  
Air Entrainment ◽  
Water Jet ◽  
Upstream Region ◽  
Level Energy ◽  
Stilling Basin

Flaring gate piers (FGPs) have been used to increase energy dissipation in stilling basins downstream of spillways. For projects with a low water head and large unit discharge together with a deep tailwater level, energy dissipation inside a conventional stilling basin is usually insufficient. This paper proposes a new partial flaring gate pier (partial FGP) scheme to intensify the energy dissipation inside the stilling basin. The results for the no FGP scheme, the conventional FGP scheme, and the partial FGP scheme were compared using a physical model study and numerical simulations. It was found that the partial FGP scheme (the alternation of flaring and no flaring gate piers in chambers) can contain the submerged hydraulic jump and high-speed water jet in the upstream region of the stilling basin. Thus, the water jet from the FGP chamber was forced to laterally diffuse, thereby intensifying the shear friction and turbulent kinetic energy and forming a vertical vortex from the bottom to the surface. Compared with the other two schemes, the flow pattern in the partial FGP scheme was improved significantly with much deeper air entrainment depth inside the stilling basin and much lower turbulent kinetic energy in the outgoing flow. The mean velocity of the outgoing flow also decreased by more than 20%. The common problems of secondary hydraulic jump outside the stilling basin were eliminated.

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