THE FLUTTER STUDY OF A TWO-DIMENSIONAL AIRFOIL WITH ASYMMETRY FREEPLAY

The dynamic response of a two-dimensional airfoil with preload asymmetry freeplay, which is of coupled aeroelastic nonlinearity and structural nonlinearity, is analyzed using numerical method. Global bifurcation of the system is investigated as the speed ratio U^*/U_L^* increases from zero to 1 gradually. The effects on the critical flutter point are investigated when the natural frequency ratio ω, freeplay clearance δ , airfoil-air mass ratio μ, preload M₀, initial deflection α_f and the initial values are varied. It is found that the chaotic motion does not occur in the asymmetry freeplay system and the amplitude of flutter motion is not affected by the initial values. Some useful suggestion for the airfoil design and maintenance are given in terms of the sensitive parameter leading to the change of the pitch-motion amplitude.