Morphing Airfoil Design for Minimum Drag and Actuation Energy Including Aerodynamic Work

A morphing aircraft can change shape in flight; one possibility for morphing would make it possible to adjust the wing cross section to the best possible shape for any flight condition encountered by the aircraft. However, there is an actuation cost associated with making these shape changes that must be included in the optimization process. A previous effort by the authors investigated a simple strain energy model to account for the actuation cost for a morphing airfoil, and a multi-objective optimization found tradeoff solutions between low-energy, high-drag and high-energy, low-drag morphing airfoils. Building upon the previous effort, this paper formulates the aerodynamic contribution to work on the morphing airfoil. This aerodynamic work term can be added to the strain energy model to compute the total energy required for changing the shape of a morphing airfoil. Studies presented in this paper illustrate computation of this aerodynamic work and illustrate how the aerodynamic work can be either beneficial or unfavorable. The effect of the morphing airfoil's relative stiffness on the multi-objective solutions is also presented.