Water‐Quality Impact Assessment for Hydropower

Daniil, Ekaterini I.; Gulliver, John S.; Thene, John R.

doi:10.1061/(asce)0733-9372(1991)117:2(179)

Cited by 11 publications

(3 citation statements)

References 3 publications

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“…Their results showed that under some conditions the effect of rotation was to increase the thickness of the withdrawal flow. Daniil et al 148 evaluated the water quality impacts of hydropower generation, with specific attention to the low dissolved oxygen that results from selective withdrawal. They suggested diversion of part of the withdrawal flow to be oxygenated over the spillway as a lowcost mitigation measure.…”

Section: Stratified Flow and Intake Structuresmentioning

confidence: 99%

Mixing and transport

Shanahan¹

1992

Water Environment Research

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Section: Stratified Flow and Intake Structuresmentioning

confidence: 99%

Mixing and transport

Shanahan¹

1992

Water Environment Research

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“…Observed calculated coefficients varied the DO deficit by 30% and showed that, for critical streams, K 2 should be measured. A method to assess the impact of hydropower on downstream water quality (including DO) was described by Daniil et at. (1991).…”

Section: Dissolved Oxygen In Streams Andmentioning

confidence: 99%

Dissolved oxygen in streams and reservoirs

Gordon¹

1992

Water Environment Research

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“…Only surface waters are replenished with oxygen through gas transfer processes resulting from wave action [3]. Hydropower projects often have hydroturbine intakes located in the hypolimnion where DO levels may drop to anoxic conditions [4,5].…”

Section: Introductionmentioning

confidence: 99%

Mass transfer studies across ventilated hydrofoils: A step towards hydroturbine aeration

Karn

Monson

Ellis

et al. 2015

International Journal of Heat and Mass Transfer

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The water discharged by hydropower facilities is a matter of increasing concern due to poor downstream water quality. The use of auto-venting hydroturbines has been suggested as one of the best ways to mitigate low dissolved oxygen levels in the downstream water. Much of the design of auto-venting hydroturbines is currently performed with computational fluid dynamics (CFD) simulations. However, there is little information available to test and verify the performance of these simulations regarding gas transfer and bubble size distribution. This paper investigates the performance of a water tunnel test-bed for CFD simulations of an auto-venting hydroturbine through the use of a ventilated hydrofoil. Bubble size distributions are measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. Higher liquid velocities, a lower airflow rate and a higher angle of attack all resulted in a greater number of small bubbles and a lower weighted mean bubble size. Bubble-water oxygen transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for oxygen transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The value of the coefficient is found to stay constant at a particular hydrofoil configuration while it varied over a narrow range of 0.52-0.60 for different hydrofoil angles of attack. This suggests that it is an appropriate coefficient for flow over a ventilated hydrofoil and possibly other flow situations. These results can be used by investigators to test and verify their CFD model against known bubble size distributions and gas transfer in a water tunnel flow that has important similarities to an auto-venting hydroturbine.

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Water‐Quality Impact Assessment for Hydropower

Cited by 11 publications

References 3 publications

Mixing and transport

Mixing and transport

Dissolved oxygen in streams and reservoirs

Mass transfer studies across ventilated hydrofoils: A step towards hydroturbine aeration

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