Leading Edge Vortex Formation on a Flapping Wing Robotic Bird

The Robird is an bird-like drone that flies by flapping its wings. It closely resembles a peregrine falcon in appearance, size and weight, but more specifically in its flapping flight performance. Drones like theRobird could might useful purposes such as bird control at airports, but their development is currently hampered by a limited understanding of the aerodynamics involved. The present study aims to identify the role of attached vortical structures on the flight performance of the Robotic bird. Particle Tracking Velocimetry (PTV) measurements were performed on a relatively large volume (200mm × 500mm × 600mm) around the flapping Robird wing. The measurement data shows two significant attached vortical structures: one on the lower side of the wing during the upstroke, and a smaller one on the upper side of the wing during the downstroke. The vortex on the lower side is accompanied by significant spanwise flow near the wing surface. The magnitude of this spanwise flow depends on the Strouhal number, which is a dimensionless measure for the flapping frequency.