Research On Laminated Damping Structure Modeling And Flutter Suppression For Wind Turbine Blade

As a kind of clean renewable energy, wind power has become a trend of new energy under the background of increasingly serious energy crisis and global environment crisis in the world today. To improve wind energy capture efficiency of the wind turbine and reduce the unit generation cost, wind turbine is developing towards the direction of large-scale. However, with the enlargement of modern wind turbine, the blade is becoming more and more "tender". As a result, vibrational coupling between the blade modals is more likely to happen, producing aeroelastic instability flutter phenomenon under the action of aerodynamic force in the wind field, elastic and inertia force. Blade flutter is harmful to the operation of wind turbine; the alternating stress caused by flutter can make the blade produce fatigue crack and even bring on rupture in severe cases.In order to overcome the flutter problem of large-scale wind turbine blade, laminated damping structure is applied to the blade in the study. In this way, the flutter energy of wind turbine blade can be turned into thermal energy dissipating in the surrounding environment through the internal friction of the viscoelastic polymer material.This article analyzes the classic flutter mechanism of wind turbine blade firstly embarking from the structural dynamics. On the basis of above work, the laminated damping structure(constraint damping structure and co-curing damping structure) is applied to the blade. The kinetic model of laminated damping blade is established based on the energy method, and the expression of structural loss factor of damping blade is derived based on the modal strain energy method. In addition, three-dimensional finite element model of a certain type of 1.5 MW wind turbine blade is established by use of the mingle unit method. Then the dynamic responses of ordinary blade and laminated damping blade under rated wind speed and limit wind speed are simulated numerically by the Newmark immediate integration method. Finally, parametric analyses of the damping layer modulus,thickness and composite off-axis fiber angle are carried out to research their effects on modal loss factor of laminated damping blade.Results show that the flutter suppression ability of laminated damping blade improves significantly compared with the ordinary blade in the same environment. Moreover, the internal load of damping blade reduces greatly, improving fatigue performance and aeroelastic stability of the blade under the limit load. Additionally, the composite off-axis fiber angle of 60°, proper material and thickness of damping layer are suggested to increase the structure loss factor of co-curing damping blade.