Evaluation of Blade Tip Edgewise Characteristics of Offshore Wind Turbines Based on Rotational Sampling Spectra
To assess the time-frequency vibration characteristics of blade rotation subjected to wind fields,a novel research on the vibration characteristics of offshore wind turbine blades based on rotation-al sampling spectrum has been developed.The blade of the NREL-5 MW offshore monopile wind tur-bine has been used as the benchmark model to investigate wind-excited edgewise vibration of the typical blade tip.Firstly,the energy perturbation mechanisms of the rotational wind spectrum are analysed based on a comparison of the fluctuating wind and the rotational sampling theory.Then the blade aero-dynamic loads are calculated by considering the Prandtl's blade tip loss correction and the Grauert cor-rection.The dynamic response patterns of the wind turbine blade in the direction of edgewise at rest and in operation are analysed in detail.The results show that the blade tip edgewise response based on the rotational sampling spectrum can accurately characterize the rotational perturbation frequency of 1～3P(0.2～0.6 Hz)of the wind turbine blades under operating conditions in the frequency domain.Moreo-ver,the upper limit amplitude of the edgewise displacement of the dynamic blade is 42.21％higher than that of the static blade response subjected to turbulent wind in the time domain.Therefore,considera-tion of rotational effects has important engineering value for blade fatigue life assessment.
万方数据
维普
