Newtonian flow over oscillating two-dimensional airfoils at moderateor large incidence

Abstract

This paper considers the problem of pitching oscillating sharp-edged, two-dimensional thin airfoils in Newtonian flow at moderate or large angles of attack. By extending and perturbing the steady flow solution past the compression surface of such airfoils, simple formulas for the unsteady surface pressure and the aerodynamic derivative are found. It is shown that moderate angles of attack have a destabilizing effect for certain pivoting positions, which increases with increasing concavity. On the other hand, pitching oscillations of concave or convex airfoils at large angles of attack are always dynamically stable.