Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Zhang, Gangfu; Chanson, Hubert

doi:10.1061/(asce)hy.1943-7900.0001505

Cited by 24 publications

(15 citation statements)

References 32 publications

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“…Energy dissipation is one of the considerations when placing auxiliary energy dissipator to prevent potential scour and cavitation in the spillway bend (Eghlidi et al 2020). Zhang & Chanson (2018) established physical models to examine the effect of step edge and cavity geometry on energy loss performance in stepped chutes. In this work, the energy dissipation rate in the spillway bend with permeable spur dikes were calculated according to the measured longitudinal velocity and water depth in laboratory experiments.…”

Section: Energy Dissipation Ratementioning

confidence: 99%

Experimental and numerical investigation of flow over a spillway bend with different combinations of permeable spur dikes

et al. 2021

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In this paper, the effects of different combinations of permeable spur dikes installed in the bend section of spillway on flow characteristics and energy dissipation rate were experimentally and numerically investigated. The results indicate that The permeable spur dikes installed in the spillway bend appreciably contributes to the improvement on the water surface uniformity, and the water surface uniformity can reach 90.13% with three permeable spur dikes installed in the bend. The permeable spur dike can lead to different degrees of decrease in the time-averaged longitudinal velocity in each zone of spillway bend. Different from previous study, no circulation zone is formed upstream and downstream of permeable spur dike due to the presence of permeable holes, and the flow upstream of permeable spur dikes could be divided into three distinctly different flow modes according to dye tracing. The presence of permeable spur dikes causes the concentration of TKE zone at concave bank of the spillway bend, except for TKE zone immediately next to the bottom plate. The TKE first increases and then decreases with the increase in the vertical distance from the bottom plate of the spillway bend, exhibiting a typical parabolic distribution. The energy dissipation rate in the spillway bend with permeable spur dike was calculated using a modified integral method, and the dissipation rate can reach as high as 21.08% with three spur dikes installed in the bend.

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Section: Energy Dissipation Ratementioning

confidence: 99%

Experimental and numerical investigation of flow over a spillway bend with different combinations of permeable spur dikes

et al. 2021

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“…Additionally, quick ramping cannot always be avoided and it can lead to extremely high loads and cavitation effects (Chirag et al 2018). Some erosion might be tolerated, and some may be avoided, for example, by aerating the areas prone to cavitation (Penghua and James 2018;Gangfu and Hubert 2018), but in-situ knowledge of the actual erosion rate is limited. In these situations, monitoring cavitation damage in real time would be beneficial.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Cavitation Pit Distributions by Acoustic Emission

et al. 2020

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Cavitation erosion in hydraulic machinery, such as in turbines and pumps, often leads to significant reduction of the service life of the affected components, with serious consequences for their maintenance costs and operation efficiency. In this study, the potential contribution of acoustic emission (AE) measurements to the assessment of cavitation damage is evaluated from experiments in a cavitation tunnel. Stainless steel samples were exposed to cavitation and damage was characterized from pitting tests carried out on mirror-polished samples. The pits were measured using an optical profilometer and cavitation damage was characterized by pit diameter distribution. In parallel, AE time signal was measured directly from behind the samples. A dedicated signal-processing technique was developed in order to identify each burst in the AE signal and determine its amplitude. The AE amplitude distribution compares well with PVDF and pressure sensor measurements from literature. It is concluded that AE signal analysis can be used to monitor the formation of pits without visual examination of the damaged surface. This provides a basis for possible future applications of nonintrusive cavitation erosion monitoring in hydraulic machines, provided the findings remain true in a more complex environment.

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“…Due to this energy dissipation along the structure, their stilling basin is made with short length [23]. Due to significant amount of kinetic energy and velocity reduction and also high value of air entrainment, the risk of cavitation will be reduced in these structures [24,25]. The process of energy dissipation over the cascade spillways has been studied experimentally and numerically.…”

Section: Introductionmentioning

confidence: 99%

Energy Loss in Skimming Flow over Cascade Spillways: Comparison of Artificial Intelligence-Based and Regression Methods

et al. 2020

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In this study, the energy dissipation of cascade spillways was studied by conducting a series of laboratory experiments. Five spillways slope angles (α) (10°, 20°, 30°, 40°, and 50°), various step numbers (N) ranging from 4 to 75, and a wide range of discharges (Q), were considered. Some data-based models were developed to explain the relationships between hydraulic parameters. Multiple linear and nonlinear regression-based equations were developed based on dimensional analysis theory to compute energy dissipation over cascade spillways. For testing the robustness of developed data-based models, M5P, stochastic M5P, and random forest (RF) were used as new artificial intelligence (AI)-based techniques. To relate the input and output variables of energy dissipation, AI-based and regression approaches were developed. It was found that the formulation based on the stochastic M5P approach in solving energy dissipation problems over cascade spillways is more successful than the other regression and AI-based methods. Sensitivity analysis suggests that spillway slope in degrees (α) is the most influential input variable in predicting the relative energy dissipation (%) of the spillway in comparison to other input variables.

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Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Cited by 24 publications

References 32 publications

Experimental and numerical investigation of flow over a spillway bend with different combinations of permeable spur dikes

Experimental and numerical investigation of flow over a spillway bend with different combinations of permeable spur dikes

Estimation of Cavitation Pit Distributions by Acoustic Emission

Energy Loss in Skimming Flow over Cascade Spillways: Comparison of Artificial Intelligence-Based and Regression Methods

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