Dissolved Oxygen Improvement by Hydroelectric Turbine Aspiration

Atmospheric oxygen introduced into the draft tube of a modern low head hydroelectric turbine by a draft tube aspiration system is shown by experimental data to be absorbed with efficiencies higher than previously reported. An analytical model of the turbine aeration system has been developed which yields aeration flow rates that are in good agreement with experimental data. A unique feature of the turbine aeration system is the application of wedge shaped deflector plates in the draft tube. The low pressure region created in the wake of the deflector plate is used to induce an aspirated air flow into the draft tube. By this procedure, appreciable air flow rates may be obtained at most efficient gate openings even for machines where the turbine is set at or below tail water elevation. The increase in dissolved oxygen levels and oxygen absorption efficiencies has been experimentally measured. The loss in turbine efficiency has been obtained from direct measurement of the output and turbine flow rate.