A geometrically exact study on the load-performance trade-offs in swept and pre-bent wind turbine blades

This study presents a comprehensive investigation into the influence of blade stacking lines, governed by a three-parameter formulation, on the dynamic response and aerodynamic performance of a 15 MW wind turbine blade. The computational framework combines Blade Element Momentum theory with Geometrically Exact Beam Theory to account for geometrical nonlinear effects. Parametric aeroelastic simulations examine blades featuring pure backward sweep, forward sweep, and pre-bend configurations, analyzing the effects of both magnitude and initiation position under steady wind conditions. Results indicate that backward sweep configurations effectively reduce flapwise root loads and tip displacements with these benefits being most pronounced below rated wind speed due to passive bend-twist coupling effects. Conversely, forward sweep demonstrates a non-monotonic influence on power output. Pre-bend configurations provide moderate power enhancement while delivering significant geometric advantages for improved tower clearance. The sweep initiation position is identified as a critical design parameter. Optimal load reduction for backward-swept blades occurs at a nondimensional span position of 0.5-0.6, whereas the most favorable power-to-load trade-off for forward sweep is achieved within the range of 0.1-0.3. These findings establish clear design guidelines for utilizing geometric blade curvature to achieve specific aero-structural objectives in large-scale wind turbine rotors.