Nonlinear aeroelasticity of an airfoil with control surface freeplay

© 1997, American Institute of Aeronautics and Astronautics, Inc.This paper presents a correlation study between numerical and experimental results for the response of a typical section airfoil with freeplay in the control surface. Since this is an inherently nonlinear system the equations of motion are integrated numerically. The typical response of this three-degree-of-freedom system, is either stationary or limit cycle prior to the onset of divergent flutter. The equations of motion are solved in state-space with the aerodynamic modeling based on Theodorsen’s theory. The freeplay condition is modeled as piecewise linear and a special procedure is developed to account accurately for this effect numerically. The physical experiments were conducted in the Duke University wind runnel. The paper describes how the response of the system changes with freestream velocity, and how these responses exhibit characteristic nonlinear behavior, in both the experimental and numerical results.