EXPERIMENTAL AND NUMERICAL SIMULATIONS OF NACA 0018 AIRFOIL UNDERGOING STALL FLUTTER WITH STRUCTURAL NONLINEARITY

摘要

The aeroelastic behaviour of a wing oscillating in large pitch amplitudes with continuos nonlinear stiffness is examined by means of wind tunnel experiments and numerical simulations. The phenomena of interest is limit cycle oscillation resulted from stall flutter. The focus of the present work is the dynamic behaviour of aeroelastic system consisting of aerodynamic nonlinearity, prescribe and unprescribe structural nonlinearity. Unprescribe structural nonlinearity manifested through changes in stiffness property during limit cycle oscillation due to fatigue. The interaction of flow separation nonlinearity with structural nonlinearities is examined. The measured and simulated aeroelastic responses are analyzed and the bifurcation behavior of the dynamic system is characterized. The analysis shows that the bifurcation behaviour is dictated structural nor from the aerodynamic nonlinearity but by a combination of the two.