Abstract
Slotted natural-laminar-flow airfoils are multi-element airfoils that employ a slot between the fore and aft elements to improve aerodynamic efficiency at cruise. Flow on the fore element pressure surface accelerates the flow through the slot which in-turn provides a pressure recovery mechanism for the suction surface of the fore element. This synergy delays the laminar to turbulent transition of the fore element leading to improved lift and a reduction in drag. These aerodynamic benefits permit aircraft designs with smaller planforms, reducing fuel burn. Smooth continuous surfaces are necessary to maintain proper flow on both the fore and aft element. For this reason, deployable surfaces to increase lift such as traditionally actuated flaps and slats can lead to premature tripping of the laminar to turbulent transition. To prevent this unwanted behavior, it is proposed that piezocomposite or other smart-material actuators are used for camber morphing of the aft element to modify lift. To this end, a parameterized model is proposed for piezocomposite airfoil morphing. The model is then applied to the aft element of a slotted natural-laminar flow airfoil with the fore element assumed as a rigid structure. A fluid-structure interaction framework is employed for determining the deformed actuated airfoil geometry subject to aerodynamic loading. Finally, a multi-objective optimization algorithm is used to generate the pareto front of two competing objective functions, maximizing excited airfoil lift and minimizing unexcited pressure induced deformation of the airfoil.
