ECN publication
Investigation into Rotor Blade Aerodynamics; Results from testing the UAE rotor in the NASA-Ames tunnel
Published by: Publication date:
ECN Wind Energy 1-6-2003
ECN report number: Document type:
ECN-C--03-025 ECN publication
Number of pages: Full text:
115 Download PDF  

During 2000 NREL (Colorado) performed an exhaustive series of measurementson their UAE phase-VI wind turbine in the 24m x 36m wind tunnel of NASA-Ames (California). In the fall of 2000 NREL organised a 'Blind Comparison' for wind-turbine research institutes. ECN participated in this benchmark with the program PHATAS. The stationary aerodynamic coefficients calculated by the participants of this 'Blind Comparison' showed large differences, in particular in stall. Based on the aerodynamic models used in the different design codes it was concluded that these differences depend among others on the airfoil coefficients-tables used and on the correction models used for rotational effects. In the winter of 2002 the aerodynamic coefficients in stall were investigated in more detail, partly based on the measured data for the S809 airfoil. These investigations resulted in an improved model for the coefficients in stall, and in suggestions for improving the models for rotational augmentation. In the program PHATAS the implementation of e.g. the tip loss factor was improved for large distances between the trailing vortices. At the moment of finishing this work, still some discrepancies remain between the measured and the calculated properties in stall. An onset is given for further research (starting with code-comparison) within the IEA Annex-XX project. Based on the discrepancies between the predicted and the calculated aerodynamic properties the needs for future developments on the existing wind turbine design codes were described.

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