The Calculation of Unsteady Aerodynamic Forces Acting on Oscillating Airfoils with Finite Amplitudes

Abstract

The calculations of unsteady aerodynamic forces acting on an airfoil were performed for flat plate, symmetrical JOUKOWSKI airfoil, NACA 4-digit symmetrical airfoil and elliptic airfoil executing sinusoidal pitching oscillation with a finite amplitude. High speed pitch up of a flat plate and of NACA 0012 airfoil were also calculated. These results show very close values to the ones with infinitesimal amplitude.
The authors' infinitesimal amplitude calculation and KÜSSNER's theory show increase of amplitude and phase lag angle of lift and moment coefficients with increase of thickness ratio of symmetrical JOUKOWSKI airfoil.