Experimental investigation of leading-edge vortex dynamics for a flapping flat plate with varying Rossby number

Leading-edge vorticity (LEV) generation is a key mechanism for delayed stall in flapping species, promoting flow attachment at high angles of attack. Understanding of such mechanisms can be applied to flapping wing MAVs and unsteady aerodynamic control. Experimental investigation of flapping flight is challenging due to the difficulty of working with live specimens and building robotics capable of performing complex wing stroke paths. We present a novel flapping flight experiment using a programmable 6-axis industrial robot to actuate a flat plate inside a wind tunnel. This allows us to mimic complex wing kinematics and control centripetal and Coriolis accelerations programmatically. Three canonical flapping procedures in forward flight, with varying Rossby number and Re=15,000, have been captured using time-resolved stereo particle image velocimetry (PIV) at 3 spanwise planes. We use proper orthogonal decomposition (POD) to understand the spectral properties of the resulting flow dynamics, in order to investigate LEV shedding versus bursting dynamics.