Papers Published

1. Kholodar, D.B. and Dowell, E.H., The influence of a nonzero angle of attack and gust loads on the nonlinear response of a typical airfoil section with a control surface freeplay, Int. J. Nonlinear Sci. Numer. Simul. (UK), vol. 1 no. 3 (2000), pp. 153 - 65 .
   (last updated on 2007/04/10)

   Abstract:
   The influence of a “frozen” harmonic gust excitation on an aeroelastic nonlinear system with a control surface freeplay at nonzero angles of attack is examined in the context of a three-degree-of-freedom airfoil. The formulation of the numerical model is based on Theodorsen's aerodynamics (1935) and is extended to account for nonlinear arbitrary motion and gust loads. By time marching of the governing equations, the system response is determined and the complex nonlinear behavior is observed. Results indicate that there is no suppressing effect due to a nonzero mean angle of attack for such a system under gust loads. A companion experimental test program in a wind tunnel with a gust generator is used to validate the numerical results. The good agreement between theory and experiment demonstrates the efficiency and accuracy of the computational method

   Keywords:
   aerodynamics;elasticity;external flows;nonlinear dynamical systems;subsonic flow;