# NREL 5MW Rotor Geometry

Dear Kishore,

I can’t answer your question on the DU airfoils. The specifications of the NREL 5-MW turbine don’t go into this detail. I suggest you contact the authors of Ref. [1] for clarification.

The center of pressure is the point in the airfoil where the aerodynamic moment is zero. However, this location is not very useful because the location moves with angle of attack. The aerodynamc center is the point in the airfoil where the aerodynamic moment does not change with lift coefficent. However, this only occurs at small angles of attack. Instead, airfoil coefficients can all be expressed relative to a fixed location in the airfoil if one includes pitching moment data in addition to drag and lift—it is this fixed location that we refer to as the aerodynamic center in FAST. That is, the aerodynamic center in FAST is simply the reference location in the airfoil about which the lift, drag, and pitching moment coefficients are defined.

The pitch axis in the NREL 5-MW turbine is assumed to pass through the chordline of each airfoil.

I hope that helps.

Best regards,

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Thanks Jason for your swift responce. The pitch axis information was the main priority, im really glad that you have solved that for me. I have tried contacting the guys at DOWEC but once agin no responce from them, maybe I will contact them again.

Kind Regards,
Kishore

Dear Jason,

I know this thread is a couple of months old now, I would just like to ask a related question if that’s ok. I am currently working as part of a research group at NTNU to develop software for aeroelastic analysis of the NREL 5MW reference turbine. We are interested in the location of the blade pitch axis for the visualisation in the software. After reading the values above that you have listed for the blade pitch axis, I am interested to know why is it that the blade pitch axis is not located at the centre of all of the cylindrical airfoil sections, so for a radius up to 9.7m?

Kind regards,

Anja

Dear Anja,

The root of the NREL 5-MW blade remains cylindrical only for a few meters; it then transitions to an airfoil shape. In the NREL 5-MW specifications report, the aerodynamics of the stations that are transitioning to an airfoil shape are approximated with drag-only airfoil data. While these innermost airfoil data tables are named “Cylinder1.dat” and “Cylinder2.dat”, this doesn’t mean that all stations are pure cylinders.

I hope that clarifies things.

Best regards,

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Dear Jason,

Thank you for the reply. That’s all clear now.

Kind regards,

Anja

Dear all,

Nando Timmer of TU Delft has graciously allowed us to publish the airfoil coordinates of the DU airfoils used by the NREL 5-MW wind turbine / DOWEC blade. Please see the spreadsheet attached.

The spreadsheet also contains the original 2D airfoil-data coefficients (without corrections for 3D effects, such as rotational stall delay).

Best regards,
DOWEC-NREL 5MW blade airfoil data-v2.xls (405 KB)

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Hi everyone,

Does anyone have the thickness/chord (t/c) distribution of the NREL 5MW blade? Figure 7 in the DOWEC report displays this information and I can digitize it, but it would be better to have the exact numbers.

DOWEC 6 MWPRE-DESIGN
DOWEC-F1W2-HJK-01-046/9
public version
H.J.T. Kooijman
C. Lindenburg
D. Winkelaar
E.L. van der Hooft

I am also having trouble understanding Table 1 in this paper. Does the “modelled from rotor span distance (input)” pertain to the “relative thickness” or the “modelled from blade thickness”?

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Dear Matias,

The airfoil thicknesses can be derived from the airfoil names. For example, “DU21” is an airfoil with t/c of 21%. This interpretation is consistent with Table 1 from the reference you’ve idenified.

My interpretation of Table 1 from that reference is that the “modeled from rotor span distance (input)” is the distance along the blade from the axis of rotation about which a given airfoil is modeled until the next row (a stepwise representation). For example, “Cylinder 1” is modeled from 1.80 to 5.98 m along the blade, “Cylinder 2” is modeled from 5.98 m to 10.15 m along the blade, etc.

Best regards,

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Hi Jason,

Thanks for your reply. The reason why I am asking this is because I want to interpolate airfoil data/profiles much like in HARP_Opt (see page 6-7 library.umaine.edu/theses/pdf/MartinH2011.pdf). I think the author of this thesis obtained the documented part of this distribution from Timmer but I’m not sure. I would like to obtain the distribution from an original source if possible. Otherwise, I will probably just use the distribution given in this thesis.

Thanks,

Matias

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Dear Jason,

Within the technical report you wrote called ‘Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine’ published in 2007, which utilizes the NREl 5MW turbine, you state that for the pitch to stall analysis you smoothed the airfoil-data coefficients near stall to eliminate the existing fluctuations that could have led to numerical problems in the BEM aerodynamic-induction solution algorithm. You did this by modified the airfoils by manually manipulating the lift coefficients.

Would it be possible to get the values of the changes you made?

Also has any further work been done on a stall operated blade for the NREL 5MW turbine, or are there airfoils that you could recommend for the NREL 5MW turbine operating in active pitch to stall control?

Thanks,
Dawn

Dear Dawn,

I’ve attached the manually smoothed airfoil data that is mentioned in that report.

NREL has not done any further work on active stall regulation of the NREL 5-MW turbine. Sorry, but I’m not sure I have any specific recommendations.

Best regards,
Smoothed.zip (13 KB)

Many thanks for this

Hello,

Did anyone build a CAD model with the Material specifications of the NREL 5-MW/61.5 m blade design of Resor? I build the blade model with NuMAD, which could not export such model in CAD Format. Can anybody help?

Best regards,
Sebastian

Jason,
I am looking at the 5MW blades and was using the pitch axis from NRELOffshrBsline5MW_Blade.dat. In my understanding the values are inconsistent with the values posted here (eg 0.25 in NRELOffshrBsline5MW_Blade.dat at BlFract = 0.0 and 0.5 here). Am I reading the information incorrectly?

Hi @Ian.Prowell,

The definition of `PitchAxis` in the ElastoDyn blade input file is different than the definition in the post above. The `PitchAxis` input specified in ElastoDyn is defined in the FAST v8 ReadMe file: https://www.nrel.gov/wind/nwtc/assets/downloads/FAST/FASTv8.16/README_FAST8.pdf, whereby
`PitchAxis = 0.5 - AeroCent`

Please note that this `PitchAxis` input is used only when AeroDyn v14 is enabled; `PitchAxis` is not used when AeroDyn v15 is enabled. When AeroDyn v15 is enabled, the aerodynamic center is specified in the AeroDyn blade input file instead.

Best regards,

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Hello every,
Recently, I have carried out numerical simulation work for NREL 5MW wind turbine and obtained some results.I would like to know if there is experimental data or standard results for this wind turbine that can be used for verification&validation.
Best regards,
Yao.Tian

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Dear @Yao.Tian,

Being a reference wind turbine, there are many publications showing simulation results of the NREL 5-MW baseline wind turbine. Can you clarify what type of simulations you are considering?

The NREL 5-MW baseline wind turbine is not a real turbine, so full-scale measurements do not exist. There are many model-scale versions of the NREL 5-MW baseline turbine, where experimental data exist, but all of these have some variations relative to the original specification.

Best regards,

1 Like

Dear @Jason.Jonkman

Thank you for your reply. I am studying the distributed force of the blade, the deformation of the blade and the flow characteristics of the wind turbine wake under various operating conditions of the NREL 5MW wind turbine. I would be grateful if you could recommend me some widely cited papers, or provide some experimental data on the relevant part.

Best regards，

dear @Jason.Jonkman

I’ve found some papers, which are very useful. Thanks all the same.

Best regards

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can you send me a copy of them