Nonlinear aeroelastic formulation for flexible high-aspect ratio wings via geometrically exact approach

The nonlinear aeroelastic modeling and behavior of HALE wings, undergoing large deformations and exhibiting dynamic stall, are presented. A fully nonlinear three-dimensional structural model, based on an exact kinematic approach, is coupled with the incompressible unsteady aerodynamic model obtained via a reduced-order indicial formulation accounting for viscous effects, in term of dynamic stall and flow separation. To this end, a modified Beddoes-Leishman model is employed. Aeroelastic simulations are performed by reducing the governing equations to a form amenable to numerical integration. Space and time integrations are conducted using a numerical scheme that includes PDE, associated with the equation of motion of the flexible wing, and ODEs, associated with the lag-state formulation pertinent to the unsteady aerodynamic loads, in a hybrid solution form. The numerical investigations show that the proposed approach is suitable for studying the aeroelastic behavior of highly nonlinear wings, for an improved understanding of the nonlinear phenomena occurring particularly in the neighborhood of the flutter boundary and in the post-critical regime.

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