Kutta–Joukowski Theorem for Unsteady Linear Aerodynamics

This paper presents the extension of Kutta–Joukowski theorem to unsteady linear aerodynamics. Starting from formulation developed by Theodorsen for solution velocity potential circulatory flows around thin, rectilinear airfoils, frequency response function between bound circulation and lift is derived. To provide a suitable time-domain applications, two finite-state approximations function, with different degrees complexity accuracy, are also proposed. The validity derived verified correlation numerical predictions given validated boundary-element-method solver flows. Furthermore, proposed applied problems concerning damped oscillatory airfoil motion gust perturbation. higher-accuracy model provides that correspond perfectly those obtained convolution integrals step responses theories Wagner Küssner. results simpler approximation satisfactory low-frequency problems, compared provided widely used approximate version available in literature.