Dynamic Responses Analysis of A 5MW NREL Wind Turbine Blade under Flap-Wise and Edge-Wise Vibrations
Keywords:Wind turbine vibration; Free vibration analysis; Flap-wise vibration, edge-wise vibration, Blade dynamic response.
A wind turbine is subjected to a regime of varying loads. For example, each rotor revolution causes a complete gravity stress reversal in the low-speed shaft, and there are varying stresses from the out-of-plane loading cycle due to fluctuating wind load. Consequently, wind turbine blade design is governed by fatigue rather than ultimate load considerations. Previous studies have adopted many different beam theories, using different techniques and codes, to model the National Renewable Energy Laboratory (NREL) 5 MW offshore wind turbine blade. There are differences, from study to study, in the free vibration results and the dynamic response. The
contribution of this study is to apply the code written by the authors to the different beam theories used with the aim of comparing the different beam theories presented in the literature and that developed by the authors. This paper reports the investigation of the effects of deformation parameters on the dynamic characteristics of the NREL 5 MW offshore wind turbine blades predicted by the different beam theories. The investigation of free vibrations is a fundamental step in the analysis of structural dynamics, and this study compares different computational structural methods and investigates their effect on the predicted dynamic response. The modal
characteristics of every model examined have been combined with strip theory to determine the dynamic response of the blade.