Nonlinearity of Two Dimensional Aeroelastic System in Transonic Flow

Abstract

Nonlinear aeroelastic phenomena of two dimensional system in transonic regime was numerically analyzed. Unsteady aerodynamics excited by pitching and heaving oscillation was investigated based on the first harmonic component of the aerodynamics computed by Navier-Stokes code. It indicated nonlinearity existed not only in the oscillation with massive flow separation but also in small amplitude less than 0.5deg pitching oscillation. Stability analysis with first harmonic component of the unsteady aerodynamics brought a bifurcation diagram, which gave an estimation of the amplitude of Limit Cycle Oscillation (LCO). The estimated amplitude of LCO was confirmed by the numerical simulation. Nonlinearity of the unsteady aerodynamics in small amplitude, which affected stability boundary, had a high correlation with transition of boundary layer.