Computational Study of Flapping Wing Response to Vertical Gusts at Low Reynolds Numbers

Abstract

This work presents a computational study of an oscillating NACA0012 airfoil’s response to vertical gusts at low Reynolds numbers. The gust is created by a cross-flow ducted floor jet and its interaction with a freestream flow causes the jet to bend downstream, thus creating a blockage effect and modifying the effective angle of attack (AoA) over an airfoil in the freestream flow. The interaction of the gust with the airfoil causes large unsteady forces, which exceed the peak static lift coefficient. As the gust becomes fully developed near the airfoil region, the airfoil exhibits a leading edge vortex formation and dynamic-stall-like phenomenon while remaining at a fixed zero degree AoA. The gust-wing interactions under dynamic pitching conditions are also studied by varying the reduced frequencies. The study shows that the effects of the gust can be mitigated by increasing the reducing frequency of the flapping wing. As a byproduct, larger lift and thrust will be produced.