Oscillating two-dimensional hypersonic airfoils at small angles of attack

Abstract

Pitching oscillations of two-dimensional pointed-nose thin airfoils with small surface curvature are considered in this paper. The analysis relies on recently developed theories for steady and unsteady hypersonic flows past such airfoils. For small surface curvature T and small reduced frequency k, a double series in i and k is assumed here and shown to lead to very simple systems of linear equations having first- or second-degree polynomial solutions. Thus, simple closed-form formulas for the unsteady surface pressure and the stability derivatives of any curved nonsymmetric airfoil (with different upper and lower surface shapes), pitching at a small angle of attack, are obtained. Results for symmetric wedges at zero incidence are compared with other available analytical and experimental calculations and the agreement is found to be generally good.