Effects of Gust Structures on the Vorticity Field of a Pitching Wing*

Animals in nature, such as birds and insects, have unique designs and techniques for flying and adapting within unsteady environments. Human-made structures, such as drones and airplanes, have fixed wings that easily malfunction when faced with inclement weather. The intention of this research is to study how birds and insects fly during gusty conditions and how the data can be applied to further improve the design and development of manufactured aircraft. Particle Image Velocimetry (PIV) measurements were used to study a pitching wing in an unsteady environment through varying flow velocities, reduced frequencies, and pitching angles. As the pitch angle increased, it created a larger disturbance in the wake of the wing causing the boundary layer to break off closer to the trailing edge of the wing. The vortices created by the gust generator caused vortex shedding along the wing if the vortex and the boundary layer had opposing direction. If the gust generator vortex and the boundary layer had similar sign, the boundary layer's vorticity would increase in magnitude. This increase of magnitude would move along the surface of the wing and eventually shed a vortex off the trailing edge of the wing.