Nonlinear aeroelastic analysis of airfoil using quasi-analytical approach

The dynamical equation of a two-dimensional airfoil with polynomial hysteresis nonlinearity is built in an incompressible flow. Then the harmonic balance method (HB) is used to solve the equation. According to a comparison with the results from numerical time marching integration, it is shown that the harmonic balance method can accurately predict the frequency and amplitude of flutter before the second bifurcation appeared. The power spectral density and time history are used to investigate the applicability of harmonic balance method. The effect of the elastic axis is also investigated. With the elastic axis closing to the airfoil midpoint, the pitch amplitude increases slightly while the plunge amplitude fluctuates with an extremum.