Structure Dynamic Response Analysis Of Horizontal Axis Wind Turbine

The modern large horizontal axis wind turbine usually undergoes large vibration and deflection, which can not only cause structure additional stress and affect structure strength, but also affect aerodynamic performance. The interaction between aerodynamics and structure will cause fluid-solid coupling process. So it's important to predict the structure dynamic response in the time-varying load.The paper firstly analyzes the blade aerodynamic performance, presents the blade element- momentum theory and its different correct methods, also analyzes the blade dynamic stall and dynamic inflow in order to calculate the rotor dynamic aerodynamic performance accurately. The analysis of the HAWT structure time-varying load provides the foundation for calculating the structure dynamic response.In order to obtain the blade and tower dynamic response to the time-varying load, the blade and tower of horizontal axis wind turbine are both simplified as a variable cross-section cantilever and discretely modelled by applying two-node beam element. Through establishing the structure dynamic equation and calculating the time-varying loads on the blade and tower, the dynamic response of the blade and tower are calculated by applying Newmark method and modal superposition principle. The different modal damping ratios by analyzing the blade aerodynamic damping are obtained and integrated them into the blade dynamic response process to obtain more accurate dynamic response results. A correspongding FEM program is developed to carry out the numerical analysis.For the blade, the rotating speed, pitch angle, blade azimuth and blade icing are taken into account to analyze the blade natural dynamic characteristics, and the centrifugal stiffening effect and aerodynamic damping are also taken into account to calculate the blade dynamic response; for the tower, the tower natural dynamic characteristics are calculated after the mass of rotor and nacelle is coupled with the tower, and the aerodynamic damping from the rotor is taken into account to analyze the tower dynamic response.A 1.0 MW wind turbine is taken as an example, the power production load case operating in turbulent wind field is simulated, the dynamic response and dynamic loads of its blade and tower are obtained. The simulation results are compared with the results calculated by GH Bladed, they are in good agreement, this verifies the model of the paper is reliable.