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.

scholarly journals Predicting the Flow Velocity at the Toe of a Labyrinth Stepped Spillway

2021 ◽  
Vol 18 (1) ◽  
pp. 20-25
Author(s):  
Jaafar S. Maatooq
Keyword(s):  
Kinetic Energy ◽  
Flow Velocity ◽  
Smooth Surface ◽  
Air Entrainment ◽  
Physical Models ◽  
Stepped Spillway ◽  
Stepped Spillways ◽  
Stilling Basin ◽  
Major Variable ◽  
Jet Velocities

The velocity at the toe of a spillway is a major variable when designing a stilling basin. Reducing this velocity leads to reduce the size of the basin as well as the required appurtenances which needs for dissipating the surplus kinetic energy of the flow. If the spillway chute is able to dissipate more kinetic energy, then the resulting flow velocity at the toe of spillway will be reduced. Typically, stepped spillway is able to dissipate more kinetic energy than that of a smooth surface. In the present study, the typical uniform shape of the steps has been modified to a labyrinth shape. It is postulated that a labyrinth shape can increase the dissipation of kinetic energy through increasing the overlap between the forests of nappe will circulating the flow that in turns leading to further turbulence. This action can reduce the jet velocities near the surfaces, thus minimizing cavitation. At the same time the increasing of circulation regions will maximize the opportunity for air entrainment which also helps to dissipate more kinetic energy. The undertaken physical models were consisted of three labyrinth stepped spillways with magnification ratios (width of labyrinth to width of conventional step) WL/W are 1.1, 1.2, and 1.3 as well as testing a conventional stepped spillway (WL/W=1). It is concluded that the spillway chute coefficient is directly proportional to the labyrinth ratio and its value decreases as this ratio increases.

scholarly journals Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

2019 ◽  
Vol 8 (4) ◽  
pp. 2109-2112
Keyword(s):  
Energy Dissipation ◽  
Laboratory Experiments ◽  
Ideal Condition ◽  
Stepped Spillway ◽  
Type Ii ◽  
Dimensional Parameter ◽  
Stilling Basin ◽  
Sequent Depth ◽  
Tail Water ◽  
The Ideal

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3 /s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (y c / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.

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 Evaluation of step�s slope on energy dissipation in stepped spillway

2014 ◽  
Vol 3 (4) ◽  
pp. 501
Author(s):  
Ali Heidari ◽  
Poria Ghasemi
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Dissipative Structures ◽  
Stepped Spillway ◽  
Stepped Spillways ◽  
Flow Energy ◽  
Hydraulic Behaviour ◽  
Basin Geometry ◽  
And Performance ◽  
Mean Kinetic Energy

Stepped spillways are kind of dissipative structures used in rivers with steep slopes to reduce the flow energy and also the scouring potential of water. This dissipation is caused through diffusion along the spillway. The reduction of energy also leads to optimize the still basin geometry and performance downstream, and thus make the project more economic. In this paper, the hydraulic behaviour of stepped spillway is investigated based on kinetic energy. The results show that the average mean kinetic energy decreases upon an appraise in stepss slope. Finally, horizontal steps are proposed. Keywords: Stepped Spillway, Mean Kinetic Energy, Dissipation, and Stepss Slope.

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.

scholarly journals Experimental and Numerical Study of the Effects of Geometric Appendance Elements on Energy Dissipation over Stepped Spillway

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 957
Author(s):  
Amir Ghaderi ◽  
Saeed Abbasi
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Numerical Study ◽  
Air Entrainment ◽  
Computational Procedure ◽  
Stepped Spillway ◽  
Construction Costs ◽  
Geometric Configurations ◽  
Inception Point

In the stepped spillway, the steps, by providing an artificial roughening bed, dissipate the flow of energy more than other types of spillways, so the construction costs for stilling basin are reduced. However, what is important in this type of spillway is increasing the effectiveness of steps in the rate of energy dissipation. The present study deals with experimental and numerical simulations regarding the influence of geometric appendance elements on the steps and its impact on the energy dissipation performances, flow patterns properties, turbulent kinetic energy, flow resistance and the Darcy roughness. The localization of inception point of air entrainment is also assessed. To this aim, different configurations are taken into account. The computational procedure is validated with experimental results and then used to test the hydraulic behavior of different geometric configurations. The results showed that the appendance elements on the steps increased the turbulent kinetic energy (TKE) values and Darcy–Weisbach friction and the energy dissipation increased significantly. By reducing the height of the elements, energy dissipation and the TKE value increase more significantly. With the appendance elements on step, the air entrainment inception locations a positioning further upstream than the flat step stepped spillway.

scholarly journals EXPERIMENTAL STUDY ON THE SIDE CHANNEL SPILLWAY AND ITS IMPACT ON THE JUMP, CROSS FLOW AND ENERGY DISSIPATION

2019 ◽  
Vol 81 (6) ◽  
Author(s):  
Djoko Legono ◽  
Roby Hambali ◽  
Denik Sri Krisnayanti
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Water Surface ◽  
Cross Flow ◽  
Side Channel ◽  
Hydraulic Jumps ◽  
Stilling Basin ◽  
Energy Dissipater ◽  
Design Discharge ◽  
The Cross

The utilization of the side channel spillway as the primary component of dam is generally due to the limitation of the available space to construct conventional spillway with design discharge capacity. Some impacts may only be identified through the hydraulic physical model study; these include the presence of the chaotic jumps at the downstream of the spillway crest, the cross flow on the steep channel, as well as the performance of the energy dissipation in the stilling basin. This paper presents the result of the experimental study of three-dimensional behaviour of flow over the entire components of the side channel spillway of Bener Dam, Indonesia. The main dam and its appurtenant components, i.e., the reservoir, the spillway crest, the spillway channel, and the energy dissipaters were built, and various discharges were introduced to study the hydraulic performance of the spillway crest, the stilling basin, the chute, and the energy dissipater. The observed data were collected and then analysed. The results show that firstly, some chaotic hydraulic jumps were found at the stilling basin at downstream spillway crest. These chaotic hydraulic jumps would produce significant vibration that may endanger the nearby structures.  Secondly, the presence of the cross flow along the steep channel downstream of the stilling basin may also need to be eliminated in such that its impact on the rise of water surface level does not create any objection. This may be carried out through the installation of baffles along the spillway channel bed. Thirdly, the presence of the hydraulic jumps at the energy dissipater basin under the design discharge has proven that the energy dissipater has performed well where local scour around the downstream structure was found to be not significant. However, to anticipate the raising of the water surface elevation at the energy dissipater basin, increasing the elevation of energy dissipater wall from +212.50 m to +215.00 m is highly recommended.

Hydraulic Model Experimental Research of SUE Hydropower Station

2013 ◽  
Vol 726-731 ◽  
pp. 3554-3558
Author(s):  
Qin Xiang Wang ◽  
Wan Qiang Chu
Keyword(s):  
Energy Dissipation ◽  
Erosion Control ◽  
Hydraulic Model ◽  
Design Flow ◽  
Hydropower Station ◽  
Power Station ◽  
Stilling Basin ◽  
Guide Wall ◽  
Structure Layout

The research of Metamorphosis hydraulic model experiment which is designed on the base of gravity similarity and turbulent resistance similarity into SUE Hydropower Station shows the structure layout and design size of SUE Hydropower Station are reasonable and overflow capacity of sluice can meet the requirements. Upstream circular-arc concrete guide wing wall and the guide wall between downstream stilling basin and power station outlet can play a role of diversion and smoothing the flow pattern. When the flow is more than design flow, the effect of energy dissipation and erosion control of stilling basin is not good. In order to enhance the effect of energy dissipation and erosion control of stilling basin, the basin shall be lengthened and baffle piers shall be set in the stilling basin to assist energy dissipation.

scholarly journals Multi-objective optimization of stepped spillway and stilling basin dimensions

2021 ◽  
Author(s):  
Fatiha Lebdiri ◽  
Abdelghani Seghir ◽  
Ali Berreksi
Keyword(s):  
Decision Making ◽  
Energy Dissipation ◽  
Dissipation Rate ◽  
Clustering Algorithm ◽  
Optimization Procedure ◽  
Energy Dissipation Rate ◽  
Stepped Spillway ◽  
Multi Objective Optimization ◽  
Stilling Basin ◽  
Multi Objective

Abstract In the present paper, an optimization procedure is proposed for stepped spillway design dimensions, which leads to maximum energy dissipation rate and minimum construction cost considering independently the chute cost and stilling basin cost. Three independent objective functions are thus simultaneously satisfied. The procedure involves four main tools: The multi-objective particle swarm optimization method (MOPSO) to find Pareto solutions in one run, the K-means clustering algorithm to reduce the size of the obtained non-dominated solutions, the pseudo-weight vector approach (PWV) to facilitate the decision making and to select some adequate solutions, and finally, CFD simulations to analyze the retained optimal solutions. The suitability of the proposed procedure is tested through an example of application. As results, a set of twenty solutions with different satisfaction levels are found and compared to existing solutions. A multi-objective optimization problem may have many different solutions, the originality of the present work lies in the proposed procedure which explores several possible ones and reduces their number to give help for the decision making. Furthermore, an approximate expression of spillway total cost is also derived as a function of flow energy dissipation rate.

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