A multidimensional two-phase flow model for the total dissolved gas downstream of spillways

Politano, Marcela; Carrica, Pablo M.; Turan, Cagri; Weber, Larry

doi:10.1080/00221686.2007.9521757

Cited by 49 publications

(14 citation statements)

References 31 publications

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“…The rate of mass transfer is computed considering that the air is soluble in water and obeys Henry's law and that the air molar composition is that of equilibrium at atmospheric pressure, which implies that the air is considered a single gas with molar averaged properties. The mass flux from gas to liquid can be expressed by (Deckert, 1992;Politano et al, 2007):…”

Section: Constitutive Equationsmentioning

confidence: 99%

“…Two-phase flow models using averaged quantities have been extensively used, mainly in the chemical and nuclear engineering communities, to simulate homogeneous tanks, bubble columns or vertical pipes. The first effort to incorporate a two-phase flow model to predict TDG at hydropower tailraces was carried out by Politano et al (2007). The authors used a two-fluid model to predict the gas and TDG distribution in a 2D cross-section passing through a spillway bay.…”

Section: Tdgmentioning

confidence: 99%

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A multiphase model for the hydrodynamics and total dissolved gas in tailraces

Politano

Carrica

Weber

2009

International Journal of Multiphase Flow

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Section: Constitutive Equationsmentioning

confidence: 99%

Section: Tdgmentioning

confidence: 99%

A multiphase model for the hydrodynamics and total dissolved gas in tailraces

Politano

Carrica

Weber

2009

International Journal of Multiphase Flow

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“…There have been many foreign studies regarding TDG supersaturation, and the results have been very enlightening [1,2]. However, their applications are limited to dams of less than 50 m in height.…”

Section: Introductionmentioning

confidence: 97%

Field observation of total dissolved gas supersaturation of high-dams

Lü

et al. 2010

Sci. China Technol. Sci.

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One of the possible negative environmental effects of hydropower stations is the supersaturation of total dissolved gas (TDG) downstream of high-dams, which can lead to gas bubble disease or even death of fish. By taking the TDG as the main study object, the paper launched the TDG field observations on Zipingpu, Three Gorges, Ertan, Manwan, Dachaoshan, Gongzui and Ertan dams in China. The factors affecting TDG generation and dissipation were explored. Energy dissipation structures, spill rates and operation patterns were the main factors causing TDG supersaturation. TDG saturations are essentially the same in the hydro-electric tail water and in the upper reaches, so hydro-electric tail water can be less TDG supersaturated through mixing downstream. The main factors affecting the dissipation process of the supersaturated TDG were tributary convergence, water depth and turbulence. TDG supersaturation was unevenly distributed in both the vertical and transverse directions. This study is important because it adds to the accumulating experience of TDG field observations of dam projects in China, and because it objectively and impartially evaluates the impacts of supersaturated TDG. The study also provides field data and references for future studies of TDG supersaturation caused by high-dams.high-dam, total dissolved gas, supersaturation, field observation Citation:Qu L, Li R, Li J, et al. Field observation of total dissolved gas supersaturation of high-dams.

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“…Our focus is on adding the effects of a range of bubble sizes to TDG production and dissipation, so for tractability, three simplifications are used: The modeled bubbles remain spherical throughout transport and diffusion. Breakup and coalescence of bubbles are not directly modeled, but are assumed to result in a normal distribution of bubble sizes as previously documented in empirical studies . TDG dissipation is only into bubbles and through the free surface to atmosphere; we neglect consumption/degeneration by biological, chemical, or other physical processes in the plunge pool. …”

Section: Methodsmentioning

confidence: 99%

“…2. Breakup and coalescence of bubbles are not directly modeled, but are assumed to result in a normal distribution of bubble sizes as previously documented in empirical studies [20,38,39]. 3.…”

Section: Overviewmentioning

confidence: 99%

Two‐phase flow simulation of supersaturated total dissolved gas in the plunge pool of a high dam

Zhang

et al. 2016

Env Prog and Sustain Energy

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Total dissolved gas (TDG) supersaturation can cause potentially fatal Gas Bubble Disease (GBD) in fish and is recognized for its severe environmental impact for high‐dam operation conditions. The generation of supersaturated TDG in high‐head hydropower project is substantially different from middle‐ or low‐head projects that have been previously studied. Although the mechanics of TDG generation in a plunge pool are clearly three‐dimensional (3D), there are great challenges and difficulties of the 3D simulation for high‐dam projects. Toward this end, a two‐dimensional (2D) model of two‐phase flow in high‐dam plunge pool is developed with established computational fluid dynamics (CFD) software. New simulation modules are developed to account for a normal distribution of bubble sizes, which allows the TDG mass transfer from bubbles and across the free surface to include bubble size nonlinearities that were previously neglected. The model is calibrated based on observations from a high‐dam hydropower project with a ski‐jump spillway and deep plunge pool. Characteristics of simulated hydrodynamics, air‐bubble distribution, and TDG distribution downstream of the high dam were analyzed. Results showed that the model achieved satisfactory calibrated simulation of dissolved gas behavior and the assumption of a bubble normal distribution could properly reflect the bubble transfer process. Residence time in the plunge pool appeared to be a key factor determining maximum modeled TDG supersaturation levels. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1139–1148, 2016

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A multidimensional two-phase flow model for the total dissolved gas downstream of spillways

Cited by 49 publications

References 31 publications

A multiphase model for the hydrodynamics and total dissolved gas in tailraces

A multiphase model for the hydrodynamics and total dissolved gas in tailraces

Field observation of total dissolved gas supersaturation of high-dams

Two‐phase flow simulation of supersaturated total dissolved gas in the plunge pool of a high dam

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