ECN publication
Towards 20MW wind turbine: High Reynolds number effects on rotor design
Published by: Publication date:
ECN Wind Energy 20-1-2012
ECN report number: Document type:
ECN-M--12-002 Conference Paper
Number of pages: Full text:
15 Download PDF  

Wind turbine sizes have grown continuously in the past. That is why the questions such as how much the wind turbine size can grow and what are the aspects that limit the growth come from have to be answered. In order to analyze these questions for the rotor of such a wind turbine, the preliminary design of a 20MW wind turbine rotor has been performed within EU 6th Framework Project UPWIND. Although the rotational speed of the wind turbine is as low as around 6 rpm, due to the growth in size very high Reynolds number values of up to 25 million have been reached. The effects of very high Reynolds numbers on the aerodynamic characteristics of the airfoils are investigated and their influences on the rotor design and performance are discussed. As a result, up to 20% reduction in the chord can be achieved due to the increase in the Cl and decrease in Cd in high Reynolds numbers. Since the change in the Reynolds numbers influences the rotor design in many respects, more detailed investigations and especially wind tunnel tests of the airfoils for very high Reynolds numbers are required in order to have reliable future large wind turbines.

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