Aeroelastic analysis of membrane airfoils and flexible-chord airfoils with trailing-edge flaps

This paper studies the static and dynamic aeroelastic characteristics of membrane airfoils and flexible-chord airfoils (deformable airfoils) with the emphasis on the effects of a trailing-edge (TE) flap which is a novel topic. Two modeling approaches are presented; the first method is the Rayleigh-Ritz method, and the second method is the finite element method which is an efficient method to study the TE flap effects. The two models are presented in the Laplace domain which enables the transient response analysis. The models adopt the potential flow aerodynamics based on the Prandtl-Glauert thin-airfoil theory and the Theodorsen's unsteady theory. The airfoils are assumed to have small deformations, so linear structural models are used. The effect of the airfoils' flexibilities on the static aeroelastic characteristics and the dynamic responses due to step and harmonic TE flap inputs is presented through a parametric study.