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Multiphase Flows

# Three-Dimensional Numerical Modeling of Cavitation and Aeration System in Dam Outlets

[+] Author and Article Information
Amir H. Nikseresht1

Mechanical Engineering Department,  Shiraz University of Technology, Shiraz, Irannikser@sutech.ac.ir

Nasser Talebbeydokhti

Head of Environmental Research and Sustainable Development CenterProfessor Civil Engineering Department,  Shiraz University, Shiraz, Irantaleb@shirazu.ac.ir

Hossein Khorshidi

Department of Civil Engineering,  Islamic Azad University, Marvdasht Branch, Marvdasht, IranKhorshidi398@gmail.com

1

Corresponding author.

J. Fluids Eng 134(9), 091302 (Aug 22, 2012) (6 pages) doi:10.1115/1.4007214 History: Received September 22, 2011; Revised July 18, 2012; Published August 22, 2012; Online August 22, 2012

## Abstract

Preservation of the live storage of reservoirs is a serious challenge for most of the countries that encounter drought. Flushing of deposited sediments through bottom outlets in a dam is one of the suitable means to transport sediments toward downstream of the dam. Due to complicated conditions of flow through bottom outlets, we are facing a lack of accurate information about the various phenomena that occurs in bottom outlets such as cavitation, corrosion, and abrasion. Cavitation is the most important problem that causes remarkable damages on the lining of these tunnels. A numerical model based on the finite volume method for fully three-dimensional (3D) open channel flow equations is incorporated into a modeling cavitation and aeration system along the dam outlets. In this study, complex two-phase turbulent flow is simulated using the $K-ɛ$ model. The pressure and velocity distribution under different conditions of gate opening and reservoir water level are computed along the tunnel and validation of the work has been obtained by comparison with measurements of a laboratory model. For both nonaerated and aerated flow, cavitation index in flow direction have been estimated and compared with each other.

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## Figures

Figure 1

General layout of the Sefidrood’s bottom outlet (the dimensions are in meters)

Figure 2

Details of 3D mesh for the bottom outlet

Figure 3

Static pressure versus distance from entrance for (a) 20% opening, (b) 60% opening, and (c) 95% opening in which 1 and 2 demonstrate the reservoir levels of 260 and 272 m, respectively

Figure 4

Flow velocity versus distance from entrance for (a) 20% opening, (b) 60% opening, and (c) 95% opening in which 1 and 2 demonstrate the reservoir levels of 260 and 272 m, respectively

Figure 5

Mass and momentum residuals for 20% opening under 260 m reservoir level

Figure 6

Cavitation index versus distance from entrance for 20% opening of the gate: (a) 260 m reservoir level and (b) 272 m reservoir level

Figure 7

Distribution of cavitation index for (a) the reservoir level of 260 m and (b) the reservoir level of 272 m

Figure 8

The aeration system including the bottom ramp, wall ramp, and air duct

Figure 9

Cavitation index in both nonaerated and aerated flows for (a) 20% opening, (b) 60% opening, and (c) 95% opening in which 1 and 2 demonstrate to the reservoir levels of 260 and 272 m, respectively

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