A parametric study of the aeroelastic behaviour of wind turbine blades in classical flutter

Abstract

A parametric study of the aeroelastic behaviour of a wind turbine blade 'typical section' in classical flutter is presented, using a new numerical model. The aerodynamic loads are computed by solving the RANS equations with a finite volume scheme while a spring model simulates the elastic behaviour. Three degrees of freedom (flap, lead/lag and pitch) are generally considered, although for the classical flutter the lead/lag is omitted. Results of four parametric studies are presented, and are compared against linearized analytical theory in order to assess the influence of key parameters, such as airfoil radial position, rotational speed and material properties on the airfoil stability and on the degree of agreement between the analytical and numerical solutions. Regarding the trends, the two methods give similar results, but the numerical method gives broader design margins. The aeroelastic behaviour becomes unstable when the blade length or the rotational speed increases, and when the stiffness decreases faster or at the same rate with the weight. © 2006 APC Power Conversion Ltd.