The aerodynamics of steady
flows around airfoils is, for the most part, properly understood and
the theoretical framework has been validated by numerous experiments. However, many techni-
cal applications operate in highly unsteady fl
ows. The added time dependency alters the steady
state solution and has far-reaching efects on theory and practical purposes. Some examples
are airplanes, Horizontal- and Vertical Axis Wind Turbines (HAWT's & VAWT's), helicopters,
underwater vehicles, and Micro Air Vehicles (MAV's). Variations in freestream velocity and
in angle of incidence cause signi cant deviations from steady fl
ow conditions depending on am-
plitude and frequency of the unsteady motion. Despite extensive efforts in understanding the
nature of unsteady
flow effects experimentally and numerically, the accurate prediction of the
unsteady aerodynamic forces remains challenging.
The towing tank research team focuses on the investigation of the flow dynamics around two dimensional airfoils at instationary conditions. Oscillatory changes in freestream velocity and angle of incidence cause significant deviations from the steady flow conditions. These deviations highly depend on amplitude and frequency of the unsteady motion. Three types of motion can be defined: surge, pitch, and plunge, which significantly influence the flow physics and cause unsteady loads.
