AN INVESTIGATION OF A MAV-SCALE FLEXIBLE FLAPPING WING IN FORWARD FLIGHT: FLOW FIELD AND AIRLOADS EXPERIMENTS WITH COUPLED CFD-CSD

Abstract

Experiments were systematically executed with a coupled computational fluid/structural dynamics aeroelastic analysis for a micro air vehicle scale flexible flapping-wing undergoing pure flap wing kinematics in forward flight. 2-D time-resolved particle image velocimetry and force measurements were performed in a wind tunnel where the free stream velocity was set to 3 m/s, Re = 15,000. Chordwise velocity fields were obtained at equally spaced spanwise sections along the wing (30% to 90% span) at the mid-downstroke and mid-upstroke of the flap cycle. The flowfield measurements and averaged force measurements were used for the validation of the 3-D aeroelastic model. The computational fluid/structural dynamics analysis combined a compressible Reynolds Averaged Navier Stokes solver with a multi-body structural solver. The objective of the combined efforts was to understand the force production of a flexible wing undergoing an avian-type flapping motion. The temporal and spanwise variation of wing pitch angle affected lift and drag, and primarily aided in producing positive thrust during both upstroke and downstroke.