Innovative Structural and Aerodynamic Design Approaches for Large Wind Turbine Blades

†† A design study of an advanced 50-meter blade for utility wind turbines is presented and discussed. The effort is part of the Department of Energy (DOE) multi-phase Blade System Design Study (BSDS) with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the one to ten megawatt size range. Two different preliminary blade designs were considered and compared in Phase I of this study. The first is a fiberglass design, while the second design selectively incorporates carbon fiber in the main structural elements. The addition of carbon results in modest cost increases and provides significant benefits, particularly with respect to blade deflection. The structural efficiency of both designs was maximized by tailoring the thickness of the blade cross sections to simplify the construction of the internal members. Inboard, the blades incorporate thick blunt-trailing-edge airfoils (flatback airfoils). Outboard, more conventional sharp-trailing-edge high-lift airfoils are used. Phase II of this project focuses on the flatback airfoil concept and the detailed design, fabrication, and testing of 9-meter versions of the blades Given that Phase II has just started, only preliminary results and future plans are presented and discussed.