Computational Investigation of Airfoil Gust Alleviation with a Jet Spoiler

A gust mitigation technique is investigated for a NACA 0012 airfoil configured with a jet functioning as a fluidic spoiler, which is located on the upper surface near the trailing edge. Large-eddy simulations test the wing-jet configuration at a zero angle of attack with Mach = 0.1 and Reynolds number = 50,000 freestream conditions, encountering a discrete one-minus cosine transverse gust of length-to-chord ratio of [Formula: see text]. Two gusts are tested, which are defined by peak effective angles of attack of [Formula: see text] and 27 deg, imparting undesirable lift forces. The first gust is characterized by gradual separation and turbulent transition of the laminar boundary layer, whereas the more challenging [Formula: see text] gust is dominated by a substantial leading-edge vortex (LEV). The jet is modeled as a velocity boundary condition activated by a proportional feedback controller with the objective of reducing the gust induced lift. A supplementary parametric study determined the optimal jet variable to be a near-vertical blowing angle of [Formula: see text], which was measured relative to the downstream direction, and a momentum coefficient of [Formula: see text]. These parameters were carried forward to detailed aerodynamic studies examining the unsteady pressure, vorticity, and skin friction, comparing the baseline and controlled gust responses. The results show the jet spoiler works by stagnating the incoming flow to create a high pressure on the upper surface while simultaneously augmenting the trailing-edge vortex, accelerating the flow underneath the wing and decreasing the lower-surface pressure, the combined effects of which mitigate the imparted lift from the gust. This control mechanism is robust and only diminishes locally by the low pressure of strong vortical structures, which are exacerbated in the LEV gust case.