Experimental investigation of 2D flexible plunging hydrofoil

It has long been hypothesized that the flight of birds and insects greatly benefits from the flexibility and morphing facility of their wings. A significant advantage that flapping flexible wing models have over quasi-steady rigid wing models was a much higher lift generation capability. Both experimental and computational studies have shown that the leading edge vortex (LEV) plays an important role in this higher lift generation. In this study, we further explore the internal mechanisms behind the production of these high lift forces. Two NACA0012 miniature wings, one flexible and one rigid, were actively plunged at various frequencies in a viscous glycerol-water solution. Two-dimensional, phaselocked particle image velocimetry (PIV) measurements were conducted to investigate the evolution of vortices. Simultaneous measurements of lift and thrust forces were taken during plunging to reveal the relationship between the force generation and the surrounding flow field. Results from the flexible hydrofoil were compared directly to results from the rigid one to reveal the influence of flexibility. These results can be used to benchmark future computational work. © 2013 by Begell House, Inc.