Aerodynamic Wind-Turbine Blade Design for the National Rotor Testbed

The NRT blade shape as viewed from the tip and at an elevation angle of 30° above the suction surface.

Sandia has designed a new wind-turbine blade 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.

1. The new blades can produce a wake that has similitude to utility scale blades (of a 1.5 MW machine) despite the difference in size and location in the atmospheric boundary layer.
2. 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.
3. A predicted power coefficient of 0.47 is achieved through the use of efficient S825 and S814 airfoils, and a region 2 tip-speed-ratio of 9.

The NRT preliminary design review took place in late October 2015 with an external review committee.