Limit cycle behavior of an airfoil with a control surface

A three-degree-of-freedom aeroelastic model with freeplay is modeled theore tically using a small number of aerodynamic eigenmodes (i.e. a reduced orde r model) based upon Peters' finite-state model for two-dimensional aerodyna mic how. The limit cycle behavior and the sensitivity to initial conditions for the onset of limit cycle oscillations are discussed. A simple and inte resting physical explanation for this behavior is presented based on harmon ic balance or describing function calculations that have been confirmed by numerical time simulations. The theoretical results are also in good agreem ent with experiment and a universal scaling law for the dependence of limit cycle oscillations and bifurcation parameters on freeplay is elucidated. ( C) 1998 Academic Press.