Scaled Aerodynamic Wind Turbine Design for Wake Similarity

A new wind turbine blade has been designed for the National Rotor Testbed (NRT) project and for future experiments at the Scaled Wind Farm Technology (SWiFT) facility with a specific focus on scaled wakes. This paper shows how to aerodynamically design new blades that can produce a wake that has similitude to utility scale blades despite the difference in size and location in the atmospheric boundary layer. The process of designing the blade is shown with a focus on which aspects of the design maintain similarity. The overall aerodynamic design philosophy ensures that the NRT blade has the same dimensionless circulation distribution as a full-scale blade so that the wake is created by the same shed vorticity. Next, the NRT blade design is presented along with its performance due to the winds at SWiFT. The design requirements determined by the SWiFT experimental test campaign are shown to be met.