GustEncounters

The flow physics That occur when wings encounter large-amplitude tranverse gusts are very rich. The flow fully separates from the wing's leading edge, forming a strong leading-edge vo. The LEV inducertex (LEV)s very low pressures on the upper surface of the wing, leading to lift augmentation. In addition to that, the gust velocity affects the wing's wake, leading to further modifications to the forces felt by the wing. During my PhD, I studied the aerodynamics of wing-gust encounters exerimentally. I used force measurments to acquire the aerodynamic loads, and high-speed particle image velocimtery to record the planar flowfield velocity around the wing at various angles of attacks and gust strengths. 

The videos above show experimental streamlines of a wing encountering a vertical gust at angles of attack 0 and 15 degrees. The richness of the flow topology is clearly illustarted in both cases. Prior to gust entry, the flow is fully attached to the wing at the low angle of attack. A Von Karm vortex street can be seen behing the wing. In contrast to the low angle of attack wing, the flow is fully stalled for the high angle of attack wing. The visualization illutsrated the wake or dead-zone behind the wing. In both cases, a large LEV form as the wings enter the gust. These vortices shed upon gust exit. 

In addition, I investigate the impact of various pitching maneeuvers on mitigating the lift impact of the gust. These maneuvers were based on open-loop and closed-loop strategies. Open loop strategies refer to maneuvers prescribed a-priori of the encounter based on full knowledge of the flow. Closed-loop strategy refers to a maneuver that is generated in real-time based on sensor measurements without knowledge of the flow. The video below shows the flowfield and force results from the closed-loop control maneuvers