Compounding Transient Airfoil Motions and the Effectiveness of Linear Superposition

This paper investigates, for the first time, effects of compounding transient airfoil motions and predictive capability linear superposition principle in vortex dominated flows. Significant increases peak lift nose-down pitching moment were observed during second two plunging at a poststall angle attack. The load response motion was estimated through with surprising level accuracy. Flowfield measurements revealed this performance to coincide constructive merging leading-edge vortices (LEVs). LEV showed sensitivity timing. Breakdown prediction coincided detachment trailing-edge formation, which disrupted merging. amplitude no discernible effect on merging, subsequently accuracy prediction. An extension periodic investigated, where single sinusoidal cycle compared true response. found capture mean increase low moderate reduced frequencies. Lift amplitude, however, captured reasonable across range frequencies amplitudes tested.