Study of Mass Transfer across Hydrofoils for Use in Aerating Turbines

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 testbed 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.