Nonlinear aeroelastic analysis of airfoil section under stall flutter oscillations and gust loads

As the desire for more flexible aircraft structures increases, so does the need to incorporate the intrinsic nonlinearities in their aeroelastic analyses. In that manner, it becomes essential to fully characterize the aeroelastic behavior and to investigate the effects that common external disturbances, such as atmospheric gust turbulence, might induce. In this work, an augmentation of the semi-empirical Beddoes–Leishman dynamic stall model to include gust loads is presented. This augmented dynamic stall model is coupled with the typical section equations of motion to yield a complete aeroelastic framework for gust-induced stall flutter analyses. The stability boundary of a classic 2-DOF typical section is investigated, and a stochastic gust response study reveals that depending on the turbulence intensity, the probabilities of reaching aeroelastic instability can be quite high even for airspeeds well below the one for linear flutter.