Estimation of Energy Dissipation of Flow Over Stepped Spillways | Chapter 8 | Engineering Research: Perspectives on Recent Advances Vol. 2

Stepped spillways have been used since ancient times, about 3500 years ago. In a stepped spillway, the spillway face is provided with a series of steps from near the crest to the toe. This type of spillway is attractive for water resource management because it dissipates energy that is within the flow. When energy is dissipated by the steps, it reduces the energy reduction that otherwise must occur at the toe of the spillway. Air entrainment inflates the water flow over stepped spillways; the bulking of water due to high air entrainment forces designers to use a greater height for sidewalls in stepped spillways and for the downstream stilling basins. The purpose of this research is to investigate the energy dissipation rate in spillways with different slopes. In the present study, nine physical stepped spillway models with slopes of 15, 25, and 45 degrees and with a number of steps varying from 5 to 50 have been constructed. The crest of the spillways has standard Ogee profiles and a constant slope extends from the crest to the spillway toe. Two different-sized flumes were used in the experiments (25 and 50 cm wide). Several physical models have been constructed in order to measure the energy dissipation. The result revealed that the two most important dimensionless factors influencing energy dissipation are the Froude number and q²/(gH_dam³). Here q is the discharge per unit width of the spillway (m³/s/m), H_dam is equal to the height of the spillway and g is the acceleration of the Earth's gravity equal to 9.81 m/s2. The results showed that slope alone is not an effective factor for energy dissipation and should be used in combination with other factors. The spillway slope and step number have less impact on the rate of energy dissipation. But for a constant discharge over a stepped spillway, increasing the spillway slope, and increasing the number of steps will increase the energy dissipation. Using multiple regressions, some useful relations for determination energy dissipating are obtained.

 

Author (s) Details

 

Farzin Salmasi
Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

 

John Abraham
University of St. Thomas, Minnesota, School of Engineering 2115 Summit Avenue St. Paul, Minnesota 55105, USA.

 

Please see the book here:- https://doi.org/10.9734/bpi/erpra/v2/3975

Exploring Two-Phase Flow Dynamics: Experimental Investigations and Computational Modeling in Smooth and Stepped Chutes | Chapter 6 | Theory and Applications of Engineering Research Vol. 2

 Cavitation damage to hardened structures is coarse in dam spillways. Cavitation can lead to cracks on the actual surface which further increases the risk of damage to hardened by means of sulfate attack, freeze-unfreeze, alkali-silica response, and others. Cavitation damage happens on concrete surfaces when discontinuities or irregularities are met in the path of speedy water flow. Stepped spillways are acceptable, economic alternatives for high-volume depository dams that require meaningful energy amusement, for structural reworking to roller-compressed concrete dams, and to advance spontaneous flow aeration. In this place study, numerical analysis of the hydraulic traits for the skimming flow government of over the stepped chute of the Zirdan Dam is carried out. A corresponding between the flow traits for stepped and smooth spillways is given. By preparing numerical models utilizing the k-ε RNG turbulence model and the multiphase combination method, a hydraulic reasoning of the flow was completed. To validate the performance of the mathematical model, field data was composed and used for confirmation. The results show that the presence of steps along the chute cause a significant decline in the length of the perimeter layer and faster aeration happens. In a stepped chute, the cavitation index is higher than the fault-finding limit along the whole length of the spillway. So, the risk of cavitation and destruction is insignificant. On the other hand, accompanying a smooth spillway, the likelihood of cavitation may happen. This negative effect (negative pressures) occurs 56 m from the ridge of the spillway on the coming after side. For the design discharge, the difference in energy wantonness for the stepped and smooth chute is 47%.

Author(s) Details:

Farzin Salmasi,
Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

John Abraham,
School of Engineering, University of St. Thomas, Minnesota, USA.

Please see the link here: https://stm.bookpi.org/TAER-V2/article/view/12949

Two New Equations for Energy Dissipation down a Stepped Spillway with Channel Slopes between 3.4∘ and 26.6∘ | Chapter 2 | Techniques and Innovation in Engineering Research Vol. 8

 A skipped spillway is a hydraulic building provided at storage and confinement dams to release flood water that cannot be retained harmlessly in reservoirs. Its purpose is to increase the strength dissipation that would have caused hazardous scour in the everyday channel below the hydraulic makeup. Several studies in the literature highlight the hurtful effects of the moving power of water falling on the type water channel. However, only a few of these studies considered the impact of strength losses developing from stepped spillways accompanying channel slopes of 3.4∘ and 26.6∘. Additionally, the existing model for predicting strength dissipation in danced spillways features a limit, the friction factor, f, that is difficult to estimate absolutely, thereby bestowing rise to its emotional estimation by those complicated with the design of treaded spillways. The authors resolve these issues by reviewing researchers' advertisements on horizontal tiptoed spillways with dam slopes 'tween 3.4∘ ≤ � ≤ 26.6∘ conducted in transition and grazing flows in large-diameter facilities accompanying phase-detection obtrusive probes. They obtain dossier sets from them, that they reanalyzed to develop two new energy disappearance models without the limit, f (the frictional factor) that govern change and skimming flows over a off-course range of operating conditions. The dossier sets from these new models compare favourably with the calculated data sets, accompanying coefficients of correlation varying from 0.95 to 0.99. These models are simple to use and produce more accurate results than the current model.

Author(s) Details:

Okechukwu Ozueigbo,
Department of Civil Engineering, Faculty of Engineering, University of Nigeria, Nsukka, Nigeria.

J. C. Agunwamba,
Department of Civil Engineering, Faculty of Engineering, University of Nigeria, Nsukka, Nigeria.

Please see the link here: https://stm.bookpi.org/TAIER-V8/article/view/9384

Boundary of Transition Flow Regime on Stepped Spillways by Physical Modeling| Chapter 1 | Current Overview on Science and Technology Research Vol. 8

 In a went down spillway, the chute face is provided with a order of steps from near the crest to the phalanx. The energy disappearance caused apiece steps reduces the required capacity of the energy person careless with money which is generally determined at the toe of the chute. Stepped spillways have been innate the past and skilled is interest in them by way of significant cost savings. The purpose concerning this study is to decide the hydraulic conditions that rule ther transition flow reign. For this purpose, 11 physical models of walked spillways were built accompanying 15, 25, and 45 degree slopes and different step numbers from 3 to 50. The breadth of flumes for installing the strode spillways were 50 and 25 cm. Results showed that dimensionless limits h/l (spillway slope) and yc/h (fault-finding depth to step altitude ratio) are effective at doing the occurrence of a change flow regime. Two barriers that are important are the “highest level for the nappe flow regime” and the “lower limit for the skipping flow regime”. Boundary defined in this place study are recommended for future uses and design of hydraulic structures.

Author(s) Details:

Farzin Salmasi,
Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

John Abraham,
University of St. Thomas, Minnesota, School of Engineering 2115 Summit Avenue St. Paul, Minnesota 55105, USA.

Please see the link here: https://stm.bookpi.org/COSTR-V8/article/view/8657

Flow Characteristics of Skimming Regime Flow over Stepped Spillways with Attention to Optimum Step Size | Chapter 3 | Current Overview on Science and Technology Research Vol. 6

 With an overflow chute, the stepped design increases the energy dissipation rate of the slide itself and reduces the size of the downstream energy dissipator. Here, a study was conducted to better understand the flow behavior in a stepped chute with scraper flow. In this work, we used different experimental setups and large-scale models previously obtained from other researchers. The current results lead to a new practical design method for step overflow with scoop flow. The design methodology includes several important aspects not foreseen in previous studies. The results apply to a variety of downcomer geometries and flow conditions typical of embankment slides. A step channel hydraulic layout drawing is provided. From these figures, the optimal number of stages is determined for maximum energy dissipation, allowing the size of downstream energy dissipators to be reduced. The method provides parameters such as the optimal number of stages, typical flow depth, average velocity at the edge of the stepped channel, sidewall height, and distillation tank type to maximize energy dissipation. Easy to implement for designers who want to

Author(s) Details:

Farzin Salmasi,
Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

John Abraham,
School of Engineering, 2115 Summit Avenue St. Paul, University of St. Thomas, Minnesota - 55105, USA.

Please see the link here: https://stm.bookpi.org/COSTR-V6/article/view/8413