Unsteady aerodynamics of a plunging airfoil in transient motion

Abstract The peak loads experienced by aircraft of all scales will typically be during gusts, turbulence or extreme manoeuvres. Understanding the aerodynamic response to these transient disturbances is therefore crucial, particularly when Leading-Edge Vortices (LEVs) occur. This fundamental study investigates a wide range plunging motions. exhibited strong dependence motion amplitude yet remained relatively insensitive duration. Within parameter tested (motion duration T i 20 τ , equivalent reduced frequency k 1, and plunge α p l e ≤ 30°), lift did not exceed that quasi-static thin airfoil theory prediction, permitting its use as safe limit for structural design. normalized change displayed weak collapse with timescale instead showed better correlation non-dimensional rate. pitching moment well rate according theoretical prediction due added-mass component plunge-up motions, but quickly diverges plunge-down At post-stall angles attack, large-scale vortex shedding was observed caused decaying oscillations in long after ends. For both NACA 0012 flat plate airfoil, first cycle occurs around subharmonic static frequency. Subsequent cycles then increase asymptotically approach 15 convective times. experimentally quantify this behavior an aspect currently missing existing reduced-order models, which could significant successive disturbances. Finally, Reynolds number insensitivity demonstrated between 20,000 150,000, even attack where can