B2.4 - Hybrid load alleviation by fluidic/reversed control and nonlinear structures

Active flow control with fluidic actuators has the potential to provide fast, efficient, and highly adaptive lift redistribution to alleviate gust loads. The actuators have a strong impact on the flow field around the wing by creating regions of separated flow or shifting the stagnation point around the trailing edge. This can be used to either influence the airfoil lift or create pitching moments that trigger a non-linear structural behavior.

This passive approach aims to use buckling elements in the wing structure that create a non-linear stiffness behavior with increasing load factor. The non-linearity is triggered by panel buckling at a critical load factor. The bending-torsion coupling then leads to a progressive reduction of angle of attack in the outer wing region in order to shift the lift distribution inboard and therefore reduce the wing root bending moment.

The objective of this concept is to achieve a highly flexible wing that is able to perform extreme load alleviation by utilizing control surfaces as flaps that will control the wing's deformation rather than directly acting as load control devices. For this purpose, aeroelastic tailoring will be utilized to adjust the stiffness of the structure in order to enhance the post reversal regime and maintain aeroelastic stability. The layout of the control surfaces will be optimized for the purpose of this approach and prescheduled deflections will be designed for alleviating maneuver loads and gust loads.