AERODYNAMIC CHARACTERISTICS OF 2-DIMENSIONAL MEMBRANE AIRFOILS

A theoretical and experimental investigation of a flow past two-dimensional inextensible membrane airfoils was made. The basic equations based on a linearized inviscid theory are transformed into a Fredholm integral equation of the second kind with an integral constraint. The equations have been solved by using the degenerate kernel method. We have measured lift, drag and pitching moment acting on two-dimensional membranes. We have also conducted a visualization of the flow past them. From the comparison between theoretical and experimental results, we obtained the following conclusions: 1) The linearized inviscid theory can predict the essential properties of the flow around membranes longer than the chord by three percent or less; 2) As the length exceeds the chord by about five percent, viscous effect dominates; 3) S-shaped membranes exist but exhibit sustained oscillations.