An investigation of the sweep effect on corrugated wings at low Reynolds numbers

Insects fly in a low Reynolds number regime in which corrugated or pleated airfoils exhibit better aerodynamic performance by suppressing the flow separation at higher angles of attack. Every insect species has its own peculiar corrugation shape while also varying in spanwise direction. The flying wing configurations are often used for MAV design, and use sweep angle to improve stability when maneuvering or encountering gusts. The airflow pattern of the Kesel-2 airfoil-based low aspect ratio MAV wings having different sweep angles at a low Reynolds range of 50,000 to 100,000 was investigated. The results show that sweep affects the maximum lift coefficient and stall angle. The lift production was found to be insensitive to changes in the Reynolds number at a particular angle of attack. Furthermore, two distinct regions comprising of an outer flow and flow trapped in the corrugations were identified.