Investigating the Effects of Flatback Airfoils and Blade Slenderness on the Design of Large Wind Turbine Blades

Design and development of large blades is very challenging due to economics, logistics, and technical barriers. Regarding the technical barriers, designs must satisfy deflection, buckling, fatigue, and stability requirements. This is a very challenging design problem, and one that becomes more challenging to do costeffectively as blades grow even longer. Sandia National Laboratories has been researching large blades for several years and identified several key design barriers for large blades in the course of this work, which include aeroelastic stability, panel buckling and gravitational fatigue loading. In this paper, we perform a series of parameter studies to evaluate design choices to address these technology barriers. The focus is on design of blades with varying slenderness using flatback airfoils with attention to aerodynamic, structural, and manufacturing trade-offs. This paper presents work in progress toward a finalized 100-meter design with flatback airfoils that meets all design loads requirements.