Optimization of tow-steered composite wind turbine blades for static aeroelastic performance

The concept of passive aeroelastic tailoring is explored to maximize power extraction from an NREL 5-MW wind turbine blade rotating in a uniform flow, where a single blade with periodic boundary conditions simulates a three-bladed wind turbine rotor. Variable-angle tow composite materials model the spanwise-variable wind turbine blade design and enable coupled bend-twist deformations under aerodynamic loading. A constrained optimization algorithm varies only the composite fiber angles along the blade span to determine their optimal distribution at four uniform inflow conditions ranging from cut-in to rated wind speeds. The computational fluid dynamics solver CRUNCH CFD and commercial finite element analysis solver Abaqus compute the static aerodynamic loads and structural deformations of the blade, respectively, until aeroelastic convergence is achieved. The resulting computational aeroelastic formulation predicts an increase in turbine power extraction by up to 14% when the blade is optimized near the cut-in wind speed, and by 7% when optimized at the rated wind speed. Using the results from optimizations at discrete wind speeds, two blade design strategies are evaluated to determine a single composite layup for the blade that maximizes power output over the range of operational wind speeds. (C) 2019 Elsevier Ltd. All rights reserved.