Abstract
At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (C Popt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger C Popt or AEP (C Popt//AEP) for the same ultimate load, or a smaller load for the same C Popt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum C popt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and C popt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project.
Highlights
The business operations of wind power companies are mainly based on onshore MW-class wind turbines, such as 1.5MW, 2MW, and 3MW wind turbines
As an extension of the study by Ge et al [7] which only focuses on the optimal power coefficient, multi-objective optimization of a 60m blade for 3MW wind turbines is performed in the present study at different Reynolds numbers, and in particular, the influence of Reynolds number on the optimal shape, ultimate load and CPopt//annual energy production (AEP) are analyzed
To make the study more general, two methods of optimization are considered: one is based on the ultimate Mxy-r and CPopt, and the other is based on the ultimate Mxy-r and AEP
Summary
The business operations of wind power companies are mainly based on onshore MW-class wind turbines, such as 1.5MW, 2MW, and 3MW wind turbines. By the software RFOIL, Ceyhan [12] and Ge et al [7] have numerically investigated the performance of several airfoils at high Reynolds number, as well as the influence of Reynolds numbers on the optimal shape of a wind turbine blade, aiming to keep the power coefficient as high as possible. As an extension of the study by Ge et al [7] which only focuses on the optimal power coefficient, multi-objective optimization of a 60m blade for 3MW wind turbines is performed in the present study at different Reynolds numbers, and in particular, the influence of Reynolds number on the optimal shape, ultimate load and CPopt//AEP are analyzed. Six types of airfoils with the thickness ranging from 40% to 18%, including DU00-W2-401, DU00-W2-350, DU97-W-300, DU91-W2-250, NACA 63421 and NACA 64618, are adopted in the present study, following many industry blades [1, 2, 5]
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