Turbine Testing in NASA
Ames 80'x120' Wind Tunnel
| The US Department of Energy’s (DOE) National
Renewable Energy Laboratory (NREL) tested a 10-meter diameter
wind turbine in the world’s largest wind tunnel. The test was
in NASA’s 24.4 by 36.6 meter (80’ by 120’) wind tunnel. This
is part of the National Full-Scale Aerodynamics Complex (NFAC) which is
located at the NASA
Research Center in Moffett Field, (Silicon Valley)
The tunnel is primarily used for determining low- and medium-speed
characteristics of full-scale aircraft and rotorcraft. The tunnel
is powered by six 18,000-hp fans that produce test section wind
up to 50 m/s (115 mph).
The NREL “Unsteady Aerodynamics” research wind turbine was extensively instrumented to characterize the aerodynamic and structural responses of a full-scale wind turbine rotor. Measured quantities included inflow conditions, airfoil aerodynamic pressure distributions, and machine responses. The turbine was tested in the tunnel in a 2-bladed, fixed-pitch (stall-controlled) configuration. It was operated at constant RPM with the rotor oriented upwind and downwind of the tower, and the hub in either rigid or damped-teetered configurations. An extensive range of pitch angles, pitch motions, yaw positions, and wind velocities were tested. The 3-week test was completed in May 2000 with the turbine operated in over 1700 different test conditions.
NREL researchers focused wind tunnel test objectives to meet recommendations of an international science panel of wind turbine aerodynamics experts. The NREL research turbine has been field-tested in various configurations since 1989 at DOE’s National Wind Technology Center located near Boulder, Colorado. It has been operated in outdoor atmospheric turbulent wind conditions up to 31 m/s (70 mph), and has been exposed to winds above 65 m/s (145 mph) with the rotor parked. Test data have been made available to the research community through International Energy Agency Annex XIV and Annex XVIII. Reports summarizing results of the atmospheric turbine tests have demonstrated the extremely complex dynamic nature of the typical wind turbine operating environment. Highly turbulent wind and sheared inflow conditions are major factors that contribute to the complexity. Testing in a controlled wind tunnel environment eliminated these factors, and resulting data provide information from which a significant portion of the complex inflow-induced operating environment is removed. This enables researchers to isolate and characterize specific dynamic stall responses and 3-D rotational effects under benign steady-state operating conditions. Resulting data are being used to improve and validate enhanced engineering models for designing and analyzing advanced wind energy machines.
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