An Investigation of the Aerodynamic Performance of a Biomimetic Insect-Sized Wing for Micro Air Vehicles

Abstract

Biologically-inspired micro air vehicles (MAVs) are miniature-scaled autonomous aircrafts which attempt to biomimic the exceptional maneuver control during low-speed flight mastered by insects. Flexible wing structures are critical elements of a nature-inspired MAV as evidence supports that the wings of aerial insects experience highly-elastic deformations that enable insects to proficiently hover and maneuver in different airflow conditions. For this study, a crane fly (family Tipulidae) forewing is selected as the target specimen to replicate both its structural integrity and aerodynamic performance. The artificial insect-sized wing is manufactured using photolithography with negative photoresist SU-8 to fabricate the vein geometry. A Kapton film is attached to the vein pattern for the assembling of the wing. The natural frequencies and mode shapes of the artificial wing are determined to characterize its vibrations. A numerical simulation of the fluid-structure interaction is conducted by coupling a finite element model of the artificial wing with a computational fluid dynamics model of the surrounding airflow. From these simulations, the deformation response and the coefficients of drag and lift of the artificial wing are predicted for different freestream velocities and angles of attack. The deformation along the span of the wing increases nonlinearly with Reynolds number from the root to the tip of the wing. The coefficient of lift increases with angle of attack and Reynolds number. The coefficient of drag decreases with Reynolds number and angle of attack. The aerodynamic efficiency, defined as the ratio of the coefficient of lift to the coefficient of drag, of the artificial wing increases with angle of attack and Reynolds number.