Biological flyers that inspire the design of micro air vehicles typically employ a combination of pitching, plunging, and rotational motions in order to optimize the aerodynamic performance. The present investigation, found in this chapter, focuses on the detailed flow structure along a low aspect ratio wing undergoing a prevalent combination of motions, i.e., combined pitch-up and rotation, in comparison with simple pitch-up and pure rotation. These maneuvers were chosen to represent generic unsteady motions, and are broadly applicable to a range of applications, including a rotating helicopter blade or propeller. Within the category of bio-inspired phenomena, the combination of pitch-up and rotation is most akin to a perching type maneuver of a biological flyer. Of particular interest is the effect of rotation on the evolution of the flow structure induced by pitch-up motion. Quantitative imaging is employed to characterize the detailed three-dimensional flow structure.
Journal Of Fluid Mechanics Article: Bross, M. & Rockwell, D. 2014 Flow structure on a simultaneously pitching and rotating wing. J. Fluid Mech. 756, 354–383. LINK