DESIGN OPTIMIZATION OF A PIEZOCOMPOSITE MORPHING MULTI-ELEMENT AIRFOIL

A slotted natural-laminar-flow airfoil design is a two-element airfoil design that employs a slot between the fore and aft elements. This slot alters the pressure recovery condition on the suction surface of the fore element, minimizing skin-friction and inhibiting the laminar to turbulent transition. These benefits reduce overall aircraft drag and increase wing lift. This allows smaller planforms, in turn, reducing fuel burn. This paper investigates the proposal that by help of piezocomposite surface actuation the aft element can be moved, rotated, and morphed to be used as a high-lift effector for take-off and landing conditions. A theoretical analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. During analysis the fore-element of the multi-element airfoil is assumed rigid. Thus, shape optimization is limited exclusively to the aft element. Airfoil morphing is achieved by way of piezocomposite actuating elements applied to the pressure and suction sides of the aft element. A genetic algorithm is used to independently optimize substrate thicknesses for each piezocomposite actuator as well as voltage, chord position and piezocomposite length. The nominal and leading edge substrate thicknesses of the airfoil are also varied. The optimized geometry for the high lift configuration is presented.