# The airfoil of AWT-27

**URL:** <https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641>\
**Category:** Airfoils\
**Created:** [June 14, 2017, 4:33am UTC](https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641 "2017-06-14T04:33:16Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Shahrzad.Iranmanesh](https://avatars.discourse-cdn.com/v4/letter/s/67e7ee/32.png) [@Shahrzad.Iranmanesh](https://forums.nlr.gov/u/Shahrzad.Iranmanesh)\
**Post date:** [June 14, 2017, 4:33am UTC](https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641/1 "2017-06-14T04:33:16Z")

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Hi,

Could you please tell me how many airfoil AWT-27 has?  
I read a report about AWT-27 which is said: “the blades are lofted from NREL S815/S809/S810 thick-airfoil sections”. What does this sentence mean? Is this mean that AWT-27 has 3 airfoils? However, based on the data available in the aerodyn file, This turbine has ten airfoils.

I would be glad if you could help me with this problem.

Best regards,  
Shahrzad Iranmanesh

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**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\
**Post date:** [June 14, 2017, 12:21pm UTC](https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641/2 "2017-06-14T12:21:30Z")

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Dear Shahrzad,

I don’t know the answer to your question as I was not the one who originally built the corresponding FAST model; perhaps someone else on this forum knows more about the design of the AWT27.

Including 10 unique airfoil data tables in FAST’s AeroDyn module does not imply that there are 10 unique airfoil shapes e.g. the unique airfoils could also imply that 3D rotational augmentation corrections were applied to the 2D airfoil data.

Best regards,

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**Author:** ![Hermann.Rochholz](https://avatars.discourse-cdn.com/v4/letter/h/85f322/32.png) [@Hermann.Rochholz](https://forums.nlr.gov/u/Hermann.Rochholz)\
**Post date:** [July 16, 2018, 10:06am UTC](https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641/3 "2018-07-16T10:06:23Z")

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I searched for AWT-27 and I found that:  
[github.com/NREL/HARP\_Opt/tree/m … t/Airfoils](https://github.com/NREL/HARP_Opt/tree/master/Source/WT_Perf/v3.05.00a-adp/CertTest/Airfoils)  
on GitHub (Thanks for putting WT\_Perf Code there).

## Therefore I assume this airfoil is not a single airfoil; it’s in fact an interpolation of this series of NREL S8XX airfoils. In geometry as well as in the polars.

The “loft” of an airplane is simply it’s surface.  
Therefore the “lofting” means the interpolation (being not so easy when surface characteristics does not fit).

Hermann R.

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**Author:** ![Danny.Sale](https://avatars.discourse-cdn.com/v4/letter/d/b4bc9f/32.png) [@Danny.Sale](https://forums.nlr.gov/u/Danny.Sale)\
**Post date:** [July 24, 2018, 11:36pm UTC](https://forums.nlr.gov/t/the-airfoil-of-awt-27/1641/4 "2018-07-24T23:36:40Z")

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agree with Jason and Hermann, the airfoil polar “AWT-27” is probably an interpolation of the polars (by Relative Thickness % between the master polars of SERI airfoils), and then it could possibly have rotational or stall-delay corrections applied (anything from the AirfoilPrep worksheet).