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Deflector Plate Turbine Aeration?Case Studies
Water quality requirements have become a focal point in recent re-licensing of hydroelectric projects. The Federal Energy Regulatory Commission has significantly increased the relevance...

Stream Water Quality Modeling in Ankara Metropolitan Area
At the time this study was undertaken, untreated wastewaters from Ankara metropolitan area (capital of Turkish Republic) were being discharged directly into Ankara Creek and its tributaries....

Tailwater Concerns and the History of Turbine Aeration
All new proposals for hydropower development and many of the almost 300 hydroelectric projects which will be relicensed before 2000 will have to address the issue of minimum dissolved...

Overview of Autoventing Turbine Technology Development Project
Low concentrations of dissolved oxygen (DO) in the discharge of hydro plants represent one of the most significant environmental concerns confronting the hydropower industry. This is especially...

Model Tests for the Evaluation of Auto-Venting Hydroturbines
The most significant environmental problem for many hydroelectric facilities is the water quality of turbine discharges. The primary water quality problem is often low dissolved oxygen...

Experimental Difficulties Encountered in Testing Air/Water Mixtures
The Tennessee Valley Authority and Voith Hydro, Inc., are conducting a joint research project to study the effects of air admission on hydraulic turbines. Francis turbine models, homologous...

Energy Losses Due to Air Admission in Hydroturbines
Admission of air at the exit of a hydroturbine runner is an attractive technique for raising dissolved oxygen levels downstream of a hydro plant. The air admission, however, is generally...

Numerical Modeling of Air/Water Mixtures for Internal Flows
The Tennessee Valley Authority (TVA) currently is working with several organizations to develop design tools for the aerating hydroturbine. Part of this effort includes the investigation...

Efficiency and Cavitation Effects of Hydroturbine Venting
Volkart and Bohac et al. have summarized much of the past work on aeration of hydroturbine releases to improve downstream water quality. Conventional alternatives for increasing dissolved...

Reviewing the Operating Objectives of the TVA Reservoir System
Under the Tennessee Valley Authority's Lake Improvement Plan, approved by the Board of Directors in February 1991, minimum flows will be provided systemwide, the releases...

The Effect of Surface Films on Concentration Fluctuations Close to a Gas/Liquid Interface
Modeling of gas/liquid mass transport requires knowledge concerning the behavior of near-surface concentration fluctuations at clean and film-covered gas/liquid interfaces. Previous measurements...

Effect of Temperature on Gas Transfer at Low Surface Renewal Rates
In order to investigate the dependence of gas transfer coefficients on temperature under conditions of low surface renewal rates, laboratory experiments were conducted using simultaneous...

Turbulent Water Aeration: Analytical Approach and Experimental Data
Analytical studies based on the statistical theory of turbulence were carried out in order to identify some relevant parameters which may be associated with the reaeration rate coefficient...

Turbulent Velocity and Gas Concentration Measurements in the Near-Surface Layer
An experiment was undertaken to study the mechanism of interfacial mass transfer. Near-surface liquid turbulence and oxygen concentration fluctuations have been measured in a grid-stirred...

Isotropic Fractionation During Air-Water Transfer of Oxygen and Nitrogen
We present empirical results that show the kinetic fractionation during gas exchange is 0.9972 ? .0002 for oxygen and 0.9987 ? .0001 for nitrogen. These values are larger than the solubility...

A Fluorescence Technique to Measure Concentration Gradients near an Interface
A new fluorescence technique which measures the concentration profile in a mass transfer boundary layer is described. It uses a tracer whose fluorescent intensity is inversely proportional...

Methane Tracer Technique for Gas Transfer at Hydraulic Structures
Using a simple headspace gas chromatographic technique, gas transfer at several hydraulic structures were investigated. Naturally occurring methane was used as a tracer gas to measure...

Measurement of Reaeration Coefficient with the Soluble Solids Probe
The results of analytical and experimental studies are presented, showing that the proposed method for indirect determination of gas transfer coefficients at gas-liquid interfaces, based...

Dissolved Oxygen and Woody Debris: Detecting Sensitive Forest Streams
Early watershed studies showed that timber harvesting and yarding could depress dissolved oxygen in nearby streams when fresh slash entered streams and streamside shade was reduced. State...

Rainfall-Reaeration Effects
The effect of rainfall intensity on reaeration has not been adequately reported in the literature. It is clear that rainfall causes surface turbulence and increases reaeration, and a significant...

 

 

 

 

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