Unsteady aeroelastic performance analysis for large-scale megawatt wind turbines based on a novel aeroelastic coupling model

With the size and adaptability of commercial wind turbines are both drastically rising, the aeroelastic performance analysis is crucial for the design and optimization of large-scale megawatt wind turbines. However, most existing aeroelastic methods based on assumption of small deflections are linear models and not suitable for flexible blades often undergoing large deflection. The present study aimed at developing a novel time-variant two-way aeroelastic coupling numerical model for calculating the unsteady load, operational modal analysis, aerodynamic damping and nonlinear large deformation is proposed in this paper. Compared to software GH bladed, this study takes aerodynamic damping analysis and aeroelastic coupling of flexible blades between unsteady load and large structural deformation into consideration. The subspace iteration method widely used in software ANSYS, hybrid beam theory, and modified Newmark-beta displacement iteration method are first combined with the blade element momentum theory (BEM). A validation is carried out by comparing the present results with commercial software GH Bladed as well as the NREL (National Renewable Energy Laboratory) public data with a maximum difference of 3.13%, it is validated that the aeroelastic model in this paper is accurate and reliable. Furthermore, the unsteady aeroelastic performance such as aerodynamic force, aerodynamic damping, and dynamic response of flexible blade is further analyzed instantaneously during time-domain simulation in detail. The results indicate that the reduction of aerodynamic load and dynamic response caused by aeroelastic coupling is mainly the out-of-plane structural deformation, yet the blade vibration-induced velocity can be ignored.