3D-PTV wake flow analysis behind a barred owl wing

Owls are slow flying non-migratory raptors. Most owls feature stealth capabilities for hunting purposes. Nocturnal owls' species feature unique combination of their wing morphology. Two of the main features are leading-edge serrations and trailing edge fringes. The leading-edge comb is theorized to be responsible for decreasing the velocity above the boundary layer while the trailing edge fringes are thought to cause the mixing of the incoming air from the top and bottom of the wing that may cause a degradation or enhancement in the turbulent field. 3D printed wing models based on a Barred owl were used: one without features and one with the leading-edge serrations and trailing edge fringes. The wings' models were tested in an open-loop wind tunnel over three angles of attack where the near wake flow was measured using 3D-PTV ('V3V'). The volumetric data enabled to fully characterize the wake region in terms of the mean and turbulence decomposed fields. The comparison to a reference wing allowed to examine the role of the unique owl wing features in alternating the wake flow field which in consequence changed the aerodynamic loads, manifest the small-scales turbulence and the pressure field which directly impact the aerodynamic noise distribution during flight.