Aeration of hydraulic turbines for increased dissolved oxygen
In warm climates, warm temperatures cause thermal stratification in hydropower reservoirs inhibiting mixing and leading to deoxygenation of waters at depth (hypolimnium). Turbines withdrawing water at depth result in low dissolved oxygen (DO) in the downstream flow having a large negative impact on the downstream riverine ecosystem. Legislation in the USA and elsewhere now requires hydropower operators to guarantee meeting minimum DO limits in downstream flows. Andritz Hydro Canada has initiated this project to optimize the elbow deflectors used in draft tube aeration, which is a technological retrofit approach not excessively impacting operation schedules. The main deliverables will be the optimization of the elbow deflectors, through a parametric study of the design parameters involved in maximizing bubble surface area and bubble concentration to result in an increase in dissolved oxygen concentration, and a set of data for validation of Andritz's Computational Fluid Dynamics model.