Wing-Tail Interaction Under Forced Harmonic Pitch

A wing-tail tandem configuration undergoing forced harmonic pitch is numerically simulated using Detached-Eddy Simulation (DES) coupled with an overset grid. This subjects a tail to a wing wake induced through forced pitch oscillations (Re=21,400, k=0.1). The study therefore captures a flow separated wake with characteristic Leading and Trailing Edge Vortices (LEV/TEVs) emanated from the wing at the higher angles-of-attack in the harmonic pitch cycles. These vortices convect downstream to interact with the tail, which are shown to be significant to its loads. Assessing the tandem system individually shows that their lift dynamics can be empirically approximated using the Theodorsen's function, but limited by stall characteristics and variances in tail lift from the wing wake encounter. This leads to a direct correlation in wing-tail dynamics where the tail lift response can be distinguished into two components; the combination of its pitch-heave by the tail moment arm, and as a periodic gust based on the separated wing wake. The periodicity and phase lag of the wake encounter by the tail suggests that wake effects are accounted for with a gust component as a function of the convective tail length. The combination of these mechanisms synthesises the tails response from both forced harmonic motion and wing wake interaction, and is shown to be significant to the entire system. This contributes to insights on wake interactions in tandem configurations under dynamic conditions.