Unsteady flat plates: A cursory review of AVT-202 research (invited)

Incompressible separation about a rigid lifting body moving through a fluid can qualitatively be segregated into broadly disorganized vortical patterns, and agglomeration of vorticity into concentrated and predictable packets. This manuscript discusses progress stemming from joint work in the NATO Science and Technology (STO) Applied Vehicle Technology (AVT) Task Group AVT-202, " Practical Extensions of MAV Unsteady Aerodynamics". AVT-202 focused on flow separation at high incidence (typically 45 degrees) for a rigid thin flat plate of aspect ratio typically 2-4, undergoing a pitching or surging maneuver, in translation or rotation. This review compares a set of experiments and computations with a proposed reduced-order model, based on superposition of noncirculatory forces from classical potential-flow, pitch-rate-effects from airfoil theory, and circulatory lift from the vortex dipole of the leading edge vortex and trailing edge vortex. We conclude from particle image velocimetry that broadly the separated flow generated by the accelerating plate can indeed be amalgamated into such a vortex pair, and the resulting model fits acceptably with the measured lift history. This offers prospect of unifying explanation for lift production across a broad range of kinematics at high incidence