Adaptive Geometry Wind Turbine Blades for Increasing Performance

Abstract

With wind turbines working to capture energy at different wind speeds rotor morphing could potentially increase energy capture over wind speeds up to the rated speed. This study examines what the optimal geometry might look like at different wind speeds, how it might differ from one speed to another, and how much increase in power and annual energy production could be realized with the optimal geometry at each wind speed. Using a blade-element theory based analysis and conducting simulations on the 1.5 MW WindPACT turbine and the 5MW NREL concept turbine, variations in blade twist and collective pitch, chord, radius, and airfoil characteristics were considered. The results indicate that there are negligible benefits to changing blade collective pitch, twist, chord, and airfoil characteristics. Only radius increase has a dominant effect, with 20% increase in radius resulting in power increase of over 45% at 8 and 10 m/s and much higher percentage increases at lower speeds, for both turbines. The increase in annual energy production is in the range of 20%. However, a larger radius increases rotor thrust.