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Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

Ge M, Fang L, Tian D - PLoS ONE (2015)

Bottom Line: To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) 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 CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//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 Cpopt//AEP.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, P. R. China.

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 (CPopt) 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 CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//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 Cpopt//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 Cpopt//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.

No MeSH data available.


Related in: MedlinePlus

Influence of Reynolds number on performance of the six airfoils (DU00-W2-401, DU00-W2-350, DU97-W-300, DU91-W2-250, NACA 63421 and NACA 64618).(A) the maximum Cl/Cd vs. Re, (B) the corresponding angle of attack at the point of maximum Cl/Cd vs. Re, (C) the corresponding Cl at the point of maximum Cl/Cd vs. Re, (D) the maximum Cl vs. Re
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pone.0141848.g004: Influence of Reynolds number on performance of the six airfoils (DU00-W2-401, DU00-W2-350, DU97-W-300, DU91-W2-250, NACA 63421 and NACA 64618).(A) the maximum Cl/Cd vs. Re, (B) the corresponding angle of attack at the point of maximum Cl/Cd vs. Re, (C) the corresponding Cl at the point of maximum Cl/Cd vs. Re, (D) the maximum Cl vs. Re

Mentions: Cl and Cd for the six airfoils at Reynolds number between Re = 1×106 and Re = 1×107 are evaluated by RFOIL. In RFOIL, the effect of rotation on airfoil characteristics is taken into consideration, for a better maximum lift coefficient and post-stall prediction [30]. For other regular airfoils, in the region of small angles, Cl increases with Reynolds number, while Cd decreases with Reynolds number, thus inducing a larger Cl/Cd at higher Reynolds number, as shown in Fig 4A. As Bak [10] stated, the airfoil performance is most sensitive around Re = 2×106, and the Reynolds number effect becomes smaller with the increase of Reynolds number. Fig 4B and 4C show α and Cl at the point of maximum Cl/Cd, respectively. Interestingly, the thicker airfoils behave differently from the thinner ones. For thicker airfoils, the maximum Cl/Cd increases with Reynolds number, but the corresponding angle of attack α and lift coefficient Cl decrease. In the region of larger angle of attack, the stall angle increases with Reynolds number, which means the maximum Cl increases at higher Reynolds number, as shown in Fig 4D. Since the Reynolds number effect is quite similar for airfoils at Reynolds number between 1×106 and 1×107, it is mainly concerned with the airfoil database at Re = 3×106 and Re = 6×106 in this paper. A comparison is to be made in detail between optimization using the airfoil database at Re = 3×106 and at Re = 6×106.


Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

Ge M, Fang L, Tian D - PLoS ONE (2015)

Influence of Reynolds number on performance of the six airfoils (DU00-W2-401, DU00-W2-350, DU97-W-300, DU91-W2-250, NACA 63421 and NACA 64618).(A) the maximum Cl/Cd vs. Re, (B) the corresponding angle of attack at the point of maximum Cl/Cd vs. Re, (C) the corresponding Cl at the point of maximum Cl/Cd vs. Re, (D) the maximum Cl vs. Re
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4631510&req=5

pone.0141848.g004: Influence of Reynolds number on performance of the six airfoils (DU00-W2-401, DU00-W2-350, DU97-W-300, DU91-W2-250, NACA 63421 and NACA 64618).(A) the maximum Cl/Cd vs. Re, (B) the corresponding angle of attack at the point of maximum Cl/Cd vs. Re, (C) the corresponding Cl at the point of maximum Cl/Cd vs. Re, (D) the maximum Cl vs. Re
Mentions: Cl and Cd for the six airfoils at Reynolds number between Re = 1×106 and Re = 1×107 are evaluated by RFOIL. In RFOIL, the effect of rotation on airfoil characteristics is taken into consideration, for a better maximum lift coefficient and post-stall prediction [30]. For other regular airfoils, in the region of small angles, Cl increases with Reynolds number, while Cd decreases with Reynolds number, thus inducing a larger Cl/Cd at higher Reynolds number, as shown in Fig 4A. As Bak [10] stated, the airfoil performance is most sensitive around Re = 2×106, and the Reynolds number effect becomes smaller with the increase of Reynolds number. Fig 4B and 4C show α and Cl at the point of maximum Cl/Cd, respectively. Interestingly, the thicker airfoils behave differently from the thinner ones. For thicker airfoils, the maximum Cl/Cd increases with Reynolds number, but the corresponding angle of attack α and lift coefficient Cl decrease. In the region of larger angle of attack, the stall angle increases with Reynolds number, which means the maximum Cl increases at higher Reynolds number, as shown in Fig 4D. Since the Reynolds number effect is quite similar for airfoils at Reynolds number between 1×106 and 1×107, it is mainly concerned with the airfoil database at Re = 3×106 and Re = 6×106 in this paper. A comparison is to be made in detail between optimization using the airfoil database at Re = 3×106 and at Re = 6×106.

Bottom Line: To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) 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 CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//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 Cpopt//AEP.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, P. R. China.

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 (CPopt) 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 CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//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 Cpopt//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 Cpopt//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.

No MeSH data available.


Related in: MedlinePlus