A Tale of Two Experiments in Unsteady and Turbulent Flows: Boundary Layers and Wind Turbines

In this talk I’ll present two experimental investigations where unsteady and turbulent flow physics form the common underlying theme.
The first study, which is fundamental in nature, was aimed at obtaining insights into the dynamics of non-linear scale interactions in a turbulent boundary layer. An active wall perturbation technique was used to apply external forcing to the flow in a targeted manner. This approach allowed for the transfer function(s) associated with interactions between specific scales (or modes) to be highlighted, leading to an interesting set of observations with broad implications for turbulence modeling and flow control.
The second study, which has a more applied flavor, deals with the aerodynamics of vertical-axis wind turbine models at full dynamic similarity to field turbines. The use of compressed-air (up to 230 bar) as the working fluid in these experiments provided access to very high Reynolds numbers that reach into the asymptotic regime for performance. Results from this study greatly aid in modeling efforts and can guide design considerations for practical turbines.
At the end I will also give a brief overview of the presently ongoing research activities in my group in the area of hypersonic flows.