Aerodynamic Exploration of Corrugated Airfoil Based on NACA0030 for Inflatable Wing Structure

The flow structures and surface pressure distributions on corrugated airfoils significantly differed from those on a conventional, smooth airfoil. An unsteady, two-dimensional computational simulation was carried out to investigate the flow behavior and associated aerodynamic performance of a group of corrugated airfoils with different levels of waviness at angles of attack from 0 degrees to 20 degrees with an interval of 2 degrees at a low Reynolds number regime (Re = 1.2 x 10(5)) and were quantitatively compared with those of its smooth counterpart. Time-averaged aerodynamic coefficients demonstrated that the corrugated airfoils have a lower lift and higher drag because of trapped vortices in the corrugations. The pressure drag of the corrugated airfoils was greater than that of the smooth airfoil. In contrast, the viscous drag of the corrugated airfoils was smaller than that of the smooth airfoil because the recirculation generated in the corrugation could reduce the viscous drag. The averaged velocity gradient in the boundary layer showed that the thickness of the boundary layer increased significantly for the corrugated airfoils because of recirculating flow caused by the small-standing vortices trapped in the valley of corrugations. The smoother the corrugated surface, the closer the aerodynamic characteristics are to those of the smooth airfoil.