Bioinspired flexible sinusoidal corrugated airfoils for enhanced aerodynamic performance in flapping-wing flight

The corrugation, formed by the spatial distribution of veins, is a general feature among insect wings and has drawn attention for its potential role in aerodynamic performance. In this study, a sinusoidal corrugated airfoil is proposed to enhance the design applicability of bio-inspired flapping-wing aircraft. Through fluid–structure interaction analysis, the aerodynamic characteristics of corrugated flapping airfoils with specific configurations are thoroughly studied under the Reynolds number of 900. It is found that the flexible sinusoidal corrugated airfoil outperforms the flat plate airfoil both in lift and thrust while staying lightweight and flexible, with the maximum increases of 311% and 119%, respectively. This advantage stems mainly from the positive influence of corrugations on flow field and vortex structure, coupled with a moderate reduction of the chord stiffness of airfoil. In particular, some useful rules in enhancing aerodynamics are revealed in the bionic wing design, from studying 10 sinusoidal corrugated airfoils. Lift is more sensitive to the leading-edge corrugation, and becomes optimal when the corrugation is convex with a width less than 30% of the chord length. Thrust is primarily influenced by the trailing-edge corrugation, with convex corrugation generating optimal thrust across various widths. The findings provide fundamental insights for wing section optimization in the design of bionic flapping wings.