Low-Reynolds-Number Effects in Passive Stall Control Using Sinusoidal Leading Edges

The objective of the present work is to investigate the application of a sinusoidal leading edge to the design of micro air vehicles. Wind-tunnel tests of wings with low aspect ratios of 1 and 1.5, rectangular planforms, and five distinct leading edges [four sinusoidal leading edges and one baseline (straight) leading edge for each aspect ratio] have been conducted. The Reynolds numbers of 70,000 and 140,000 have been analyzed. For the higher Reynolds number, a proper combination of amplitude and wavelength can lead to a substantial increase in lift for angles of attack greater than the baseline stall angle. Maximum lift coefficient gains of the order of 45% were achieved by combining both large amplitude and large wavelength. At the lower Reynolds number, the benefits can be extended to low angles of attack, leading to a dramatic increase in the range of operation. The results depend strongly on the aspect ratio.