Gust response at high angles of attack

The responses of a NACA0012 airfoil and a large-aspect-ratio wing, subjected to gust excitation about high mean angles of attack, close to stall, are presented here. Reynolds-averaged Navier–Stokes turbulent simulations were employed to compare the gust responses at high and low mean angles of attack. It was observed that, for a rigid configuration at incipient stall conditions, the peak aerodynamic loads due to short gust lengths are higher than their counterparts at low angles of attack. However, they decrease asymptotically with increasing gust length. A convolution-based gust analysis methodology that can predict accurate gust loads at incipient stall conditions is also presented. The convolution-based method was employed to perform tuned-gust analysis with varying wing stiffness. The results show that the changes in peak modal displacements with wing flexibility at incipient stall are significantly different from their low-angle-of-attack counterparts, resulting in significantly different critical gust lengths, and 40% lower peak bending moment for a moderately flexible wing. This shows that high-fidelity gust analysis is imperative at incipient stall conditions, and the convolution-based method provides a computationally efficient yet accurate approach to achieve this.