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Previous experimental studies on static, bioinspired corrugated wings have shown that they produce favorable aerodynamic properties such as delayed stall compared with streamlined wings and flat plates at high Reynolds numbers (Re 10 4). The majority of studies have been carried out with scaled models of dragonfly forewings from the Aeshna cyanea in either wind tunnels or water channels. In this paper, the aerodynamics of a corrugated airfoil was investigated using computational fluid dynamics at low Reynolds numbers of 500, 1000, and 2000. A structural analysis was also performed using the commercial software SolidWorks 2009. The complex vortex structures that formed in the corrugated airfoil valleys and around the corrugated airfoil are studied in detail. Comparisons are made with experimental measurements at different Reynolds numbers and with simulations of a flat plate. The study shows that, at low Reynolds numbers, the corrugation does not provide any aerodynamic benefit compared with a flat plate. Instead, the corrugated airfoil generates more drag than the flat plate. Structural analysis shows that the wing corrugation can increase the resistance to bending moments on the wing structure with reduced thickness and weight.

Abstract:The development of the lift generated by a leading edge vortex (LEV) across a flat plate experiencing a pitch-up motion is investigated to understand the LEV's influence on lift generation. The flow field around the pitch-up plate is simulated by solving the Navier-Stokes equations on composite overlapping grids. The pitch-up angle was from 0 to 45 degrees and the Reynolds number was 500. The Q-criterion method was used to isolate vortex structures from shear layer vortices in order to assess the circulation of the LEV. The calculated circulation due to LEV was then compared to the computed lift from simulation for a better understanding of the effect of the LEV on lift generation. Using the non-circulatory component of Theodorsen's theory, we separate the total lift into lift due to the plate rotation (non-circulatory lift) and lift due to aerodynamic effects (circulatory lift). Our results showed that the non-circulatory force only contributes 10-20% of the total lift and the remaining is due to the LEV. We also found that the LEV growth mainly depends on time but not the angle of attack. However, the circulation strength of the LEV depends on the pitch rate.

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