Analysis of limit cycle flutter of an airfoil in incompressible flow

Both experimental and theoretical analyses are perfomed to investigate several types of self-excited oscillations of a two-dimensional wing model with non-linear pitching stiffiness. Free play non-linearity receives especial attention. In the low speed wind tunnel test of the wing model with free play in pitch, an interesting case of double limit cycle flutter is found. Subsequent harmonic balance analyses ascertain not only these two sustained oscillations, but also two other unstable limit cycles. A digital simulation method is also used for flutter analysis. The theoretical results agree well with the experimental data.