Investigations on the effects of structural damping on vortex-induced vibration response of an airfoil at a high angle of attack via the aero-damping map

Large-scale modern wind turbines at standstill are prone to vortex-induced vibrations. In this study, we propose the use of aero-damping map investigate complex vibration responses turbine airfoil 90° attack angle with different levels structural dampings. The amplitude and response frequency in lock-in condition soft conditions agree well contour line on which sum aerodynamic damping is equal zero. mechanism explored from aspect energy transfer that when equilibrium state cannot be maintained natural due high damping, system locks a between vortex shedding stationary achieve lower more absorption air. transient beat also investigated combined dynamic mode decomposition method. It found von Kármán coexist unsteady flow field during vibration. competition two modes causes an intermittent alternating stage unlock-in higher hence resulting amplification attenuation alternately.