Aerodynamic analysis of transitional wings encountering high amplitude streamwise gust

Abstract

We are interested here in the effect of high amplitude streamwise gusts felt by fixed rigid wings at pre-stall angles of incidence in low Reynolds numbers ($Re\approx 50 \times 10^3 - 200 \times 10^3$) flow conditions. An experimental rig has been developed to reproduce a cyclic variation of the freestream axial velocity representative of the perturbations micro-aerial vehicles can encounter in a urban environment. The temporal evolution of the aerodynamic forces (lift, drag and pitching moment) recorded during the gust show significant deviations from the quasi-static predictions that unsteady but inviscid methods are unable to capture. These deviations appear to be related to the dynamic of both the laminar separation bubble and the laminar separation without trailing edge reattachment, also known as the ``short" and ``long bubble" respectively.