A COMPREHENSIVE NUMERICAL MODEL FOR HORIZONTAL AXIS WIND TURBINES AEROELASTICITY

This paper deals with a computational aeroelastic tool aimed at the analysis of performance, response and stability of horizontal axis wind turbines. It couples a nonlinear beam model for blades structural dynamics with an unsteady state-space sectional aerodynamic load model taking into account dynamic stall and inflow effects induced by rotor wake. An extension of 2D static coefficients for high angles of attack is provided to characterize operations in deep stall regime. The Galerkin method is applied to the aeroelastic differential system, with the introduction of a novel approach for the spatial integration of the additional aerodynamic states related to wake vorticity and dynamic stall. Periodic blade responses are determined by a harmonic balance approach and a standard eigenproblem is solved for the stability analysis. Validation of the applied unsteady, sectional aerodynamics model is performed through comparisons with experimental data concerning NACA0012 and S809 airfoil undergoing oscillatory pitch motion. Further, results obtained by the aeroelastic code including dynamic stall modeling applied to the NREL/NASA Ames Phase VI two-bladed rotor in axial flow are presented, with comparisons to available experimental and numerical data.