Study of mass transfer across hydrofoils for use in aerating turbines

Abstract

Hydroelectric projects often have a low tailwater dissolved oxygen (DO) concentration. Low DO levels negatively impact the biota of the water body and are often regulated. Auto-Vented Turbines (AVTs) are one form of DO mitigation that is typically successful and cost-effective. Saint Anthony Falls Laboratory (SAFL) at the University of Minnesota (UMN) is partnering with the Department of Energy (DoE) and Alstom Engineering to conduct research developing a conventional hydropower turbine aeration test-bed for computational routines and a software tool for predicting the DO uptake of AVTs. The focus of this thesis is on the development of the test-bed through the conduct of physical experiments focused on measuring mass transfer across bubbles in various flow conditions. This test-bed will be a valuable database for verification of numerical models of DO uptake. Numerical models can simulate the parameters of the water tunnel and experimental set-up, then verify their accuracy by simulating the air entrainment rate, bubble size and mass transfer of the test-bed. The findings presented herein can lead to further optimization of AVTs, as well as reduce cost and regulatory uncertainty prior to hydropower relicensing or development.