Research On Inerter-based Dynamic Vibration Absorbers For Vibration Reduction Of Wind Turbine Blades

In this paper,five different inerter-based dynamic vibration absorbers which are obtained by replacing the damper in the traditional tuned mass damper（TMD）,are used to suppressing the edgewise vibrations of the rotating blades induced by external loads including gravity and wind loads.The main work of this paper is as follows:1.The wind turbine blade is modeled as a rotational cantilever Euler-Bernoulli beam with varying mass and stiffness along the length.And the Euler-Lagrange equation is used to establish the motion equations of the blade mounted with five different inerter-based dynamic vibration absorbers respectively.2.The formulas of parameter calibration for all five inerter-based dynamic vibration absorbers are derived by pole-placement method,which are essentially obtained by restricting the roots of the characteristic equation of the system by the conditions of equal modal damping ratio and the conditions at the bifurcation points.And the effectiveness of pole-placement method is verified by comparing with numerical H_∞optimization and their frequency domain performance is also analyzed.3.TheH₂ performance indicators of the blade damping systems are introduced,and based on the analytical calculation method ofH₂ performance,the analytical expressions of theH₂ performance indicators of all five inerter-based dynamic vibration absorbers considered in this paper are derived.On this basis,the problem of solving the optimalH₂performance of the system is reduced to the solution of an optimization problem.Through the results of numerical optimization,the relationship between mass ratio,blade rotation speed and damper installation position and the optimalH₂ performance and structural parameters of the five inerter-based dynamic vibration absorbers are compared and analyzed.4.The external loads on the wind turbine blade are calculated,which are mainly divided into two parts:the gravity loads of the blade itself and the wind loads.The gravity loads of the blade are determined by the structural parameters of the blade and change periodically with the rotation of the blade.The wind loads can be calculated by Blade Element Momentum（BEM）theory,and the Prandtl’s tip and root loss factor and Glauert correction are used to correct the assumption of BEM theory that the number of blades is infinite and the inaccurate calculation of induced velocity.5.The response of the blade damping system composed of five kinds of inerter-based dynamic vibration absorbers and blade under the action of external loads is simulated.And through comparative analysis with the response of the uncontrolled blade,the damping performance of each structure is verified,where the structure parameters of the five inerter-based dynamic vibration absorbers are obtained by the pole-placement method and theH₂optimization respectively.