Numerical Simulation of Air-Core Vortex at Intake

Rabe, Behrouz Khadem; Najafabadi, Seyyed Hossein Ghoreishi; Sarkardeh, Hamed

doi:10.18520/cs/v113/i01/141-147

Cited by 19 publications

(2 citation statements)

References 24 publications

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“…Their ndings have shown that the rotational ow power for the ow through the CPK spillway is many times smaller than that for shaft spillways; This con guration also produces outstanding hydraulic e ciency, such as raising the spillway crest length by at least 200 percent without altering the shaft spillway's global size, thus increasing the discharge by up to 6 times relative to a shaft spillway. Also (Sarkardeh, 2017b), (Khanarmuei et al, 2019), (Tahershamsi et al, 2018), and (Rabe et al, 2017) examined vortex ows in the intakes. (Taştan and Yıldırım, 2018) investigates the effect of intake geometry on the occurrence of a free-surface vortex.…”

Section: Introductionmentioning

confidence: 99%

Using a Deflector and Crest Design to Make a Safe Spillway Operation

Esmaelizadeh

Lashkar-Ara

2021

Preprint

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Floods are an important hazard throughout the world. The origins of some floods are a dam failure, hydraulic structure failure as well as an improper performance of the spillway. Among these, shaft spillways are known as a flood drainage system in dams, which is submerged by increasing the level of the reservoir, so that reduces the spillway efficiency and causes over topping. Investigations show that using deflector and aeration in shaft spillways will cause the flow pattern to improve. In this study, it has been tried to experiment on the impact of a deflector located in the throat and inlet geometry of the crest on the improvement of the hydraulic performance of the shaft spillway, and decrease to some extent the hazard induced by lack of timely drainage of floods in dam reservoirs. In order to investigate the deflector effect, three constriction specimens in shaft throat with constriction area to shaft area ratio (Ad/Ai) of respectively 0.75, 0.5 and 0.25 were considered as scenarios. In each scenario, the conditions of the flow passing through 12 different specimens of spillway with Crown Wheel inlets were tested and the results were compared with the flow conditions in crown wheel spillways without deflector (reference model). The results showed that the use of deflector has an important role in reducing vortex flows and stabilizing changes in the water level of the reservoir, and also increases the discharge coefficient of the flow. The studies on reference models also showed that Crown Wheel inlets (C.W.) improved shaft spillway performance, with C.W. spillways having an average discharge coefficient of 32% higher than shaft spillways. Finally, considering optimal deflector factors and C.W. geometry, an optimal model was proposed for flood reservoir conditions.

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Section: Introductionmentioning

confidence: 99%

Using a Deflector and Crest Design to Make a Safe Spillway Operation

Esmaelizadeh

Lashkar-Ara

2021

Preprint

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“…Their findings showed that the rotational flow power for flow through a CPK spillway is many times lower than that for shaft spillways. Additionally, (Sarkardeh, 2017b), (Khanarmuei et al, 2019), (Tahershamsi et al, 2018), and (Rabe et al, 2017) examined vortex flows in intakes. (Taştan and Yıldırım, 2018) investigated the effect of intake geometry on the occurrence of a free-surface vortex.…”

mentioning

confidence: 99%

Effect of deflector and crest geometry on submerged flow in a shaft spillway

Esmaeili,

Lashkar-Ara

2024

Preprint

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In this study, the impacts of a deflector located in the throat and inlet geometry of the crest on improving the hydraulic performance of a shaft spillway were investigated, and the hazards induced by the lack of timely drainage of floods in dam reservoirs were decreased to some extent. To investigate the deflection effect, three constriction specimens in the shaft throat with constriction area-to-shaft area ratios (Ad/Ai) of 0.75, 0.5 and 0.25 were considered as scenarios. In each scenario, the flow conditions through 12 different spillway specimens with crown wheel inlets were tested, and the results were compared with the flow conditions in crown wheel spillways without a deflector (reference model). The results showed that the use of a deflector has an important role in reducing vortex flows, stabilizing changes in the water level of the reservoir and increasing the discharge coefficient of the flow. Studies on reference models have also shown that crown wheel inlets (C.W.) improve shaft spillway performance, with C.W. spillways having an average discharge coefficient 32% greater than that of shaft spillways. Finally, considering the optimal deflector factors and C.W. geometry, an optimal model was proposed for flood reservoir conditions.

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Experimental and numerical investigation on effect of trash rack on flow properties at power intakes

et al. 2020

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In the present experimental and numerical research, the flow behavior in a reservoir and horizontal water intake was analyzed in the presence of surface vortices. To do so, velocity field, vortex strength, and Reynolds number in different horizontal sections in the reservoir and the energy loss and entrained air volume at horizontal intake pipe at three different relative submerged depths (S/D = 1, 1.5 and 2) and five intake Froude numbers (Fr = 0.8, 1.0, 1.2, 1.4, and 1.6) were investigated by installing two trash racks with 64% and 70% openings and one intake without trash rack. The velocity field and vortex strength were measured using Particle Tracking Velocimetry. Reynolds number, velocity, energy loss, and entrained air volume at horizontal intake pipe were computed by numerical simulations. The commercially available computational fluid dynamics program Flow‐3D, was used for the numerical modeling. Numerical simulations were validated by the experimental data. The experimental tests revealed that trash rack presence has a significant effect on reducing the vortex strength and velocity on the water surface. The vortex strength was decreased by 11% and 16% in the trash racks with 70% and 64% opening, respectively. Energy loss clearly increased with the installation of a trash rack. Energy loss in the trash rack with 70% opening was approximately 19–26%. In addition, some relationships were provided for calculation of vortex strength, velocity, and local energy loss in the water intake, which are in good agreement with the studies in the literature.

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Numerical Simulation of Air-Core Vortex at Intake

Cited by 19 publications

References 24 publications

Using a Deflector and Crest Design to Make a Safe Spillway Operation

Using a Deflector and Crest Design to Make a Safe Spillway Operation

Effect of deflector and crest geometry on submerged flow in a shaft spillway

Experimental and numerical investigation on effect of trash rack on flow properties at power intakes

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