Accession Number : ADA329707

Title :   Control of Nonlinear Behavior - Experiments

Descriptive Note : Final rept. 10 Jun 93-9 Sep 96

Corporate Author : DUKE UNIV DURHAM NC DEPT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE

Personal Author(s) : Virgin, L. N. ; Dowell, E. H.

PDF Url : ADA329707

Report Date : AUG 1997

Pagination or Media Count : 7

Abstract : The full effects of the problem of control surface freeplay in an aeroelastic system are examined in the context of a three degree of freedom aeroelastic typical section. A computationally efficient numerical model of the nonlinear system is presented, in which the control surface freeplay is modeled as a system of piecewise linear state space models. The system response is determined by time marching of the governing equations using a standard Runge Kutta algorithm in conjunction with Henon's method for integrating a system of equations to a prescribed surface of phase space section. An experimental model which closely approximates the three degree of freedom typical section in two-dimensional, incompressible flow has been created to validate the theoretical model. Consideration is also given to modeling realistically the structural damping present in the experimental system. Limit cycle oscillations are studied numerically and experimentally. The numerical model captures the full range of nonlinear behavior present in the physical system, including decaying oscillations, limit cycles, quasiperiodicity, nonperiodicity, possible chaos and divergent flutter.

Descriptors :   *AERODYNAMIC STABILITY, *AEROELASTICITY, *AERODYNAMIC CONTROL SURFACES, ALGORITHMS, CHAOS, DAMPING, DEGREES OF FREEDOM, FREE STREAM, BIFURCATION(MATHEMATICS), INCOMPRESSIBLE FLOW, FLUTTER, TRAILING EDGES.

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE