Structural Optimization on Composite Blades of Large-Scale Wind Turbines

Abstract

Turbine blades used in large-scale, horizontal-axis wind turbines are usually made from composite materials to reduce the weight while attaining a reasonable strength to weight ratio. The design of large wind turbine blades must consider both their aerodynamic efficiency and structural robustness. This paper presents an optimum design scheme for composite wind turbine blades. The first optimization phase produces the aerodynamic outer shape of a blade framed by airfoils with optimum cord lengths and twist angles along the blade spanwise direction. The second phase provides optimal material distribution for the composite blade. Loadings on the blade are simulated using wind field and wind turbine dynamics codes. The maximum loads on the turbine blade are then extracted and applied to a parameterized finite element model. A design example of a 3 MW wind turbine blade considering one critical load case with a mean wind speed of 25 m/s is demonstrated. The optimization result shows that although the initial blade model is an infeasible design, the optimization process eventually converges to a feasible solution with an optimized mass of 8750.2 kg.