The Experimental Investigation of Vortex Wakes from Oscillating Airfoils

Abstract

The ability to control large vortices in the wake of an unsteady body is studied experimentally. A single airfoil in a uniform flow is forced to oscillate sinusoidally about its aerodynamic center and the resulting wake is expected to be dominated by large coherent vortices The wakes for several different oscillation waveforms are studied and a model describing the evolution of the vortices as they progress downstream is developed and compared to the experimental data. The investigation then expands to 2 airfoils in a tandem configuration where an upstream airfoil produces a predictable and well studied wake which a downstream airfoil attempts to modify in some prescribed manner. The resulting velocity field is measured experimentally with PIV and custom vortex detection software is developed.