Help about BEM and NREL's Phase VI

Discuss the theory and modeling of rotor aerodynamics.

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Wesley.Miguel
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Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Mon Apr 18, 2016 9:45 pm

First of all, thank you for the opportunity to be a member of this forum. :)

I'm currently doing an iteration in Excel about NREL's Phase VI wind turbine for validation purposes.

I tried using 6 m/s as the free stream velocity and the radial sections selected (Fig 1) are attached on this post.

However, when I am about to compute the torque using the Trapezoidal approach (Fig 2) and use the value to compute the power, it did not match the rating of 19.8 kW. Any suggestions about these?

----

The other approach that I am looking, is analyze another study that employs NREL's Phase VI wind turbine. Though it operates on a different speed, (e.g. 7 m/s) I am observing if the induction factors of a certain section (e.g. r/R = 0.3) matches with my excel computation, then this will validate things.
Last edited by Wesley.Miguel on Tue Jun 28, 2016 6:41 am, edited 1 time in total.

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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Tue Apr 19, 2016 9:27 am

Dear Wesley,

I'm not sure I understand your question. I don't see in your post what values of A_i and B_i you used and what the source of that data is.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
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Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Wed Apr 20, 2016 8:39 am

Oh, my apologies sir. and thanks for replying :))

sir, I'll start with the BEM iteration, if I will use 6 m/s as free stream velocity, when the BEM iteration converges, the power computed is 19.8kW? Or the 6 m/s only indicates that this is the cut-in speed? I've seen several studies that used more than one velocities (e.g. 7 m/s, 15 m/s and so on..)

kind regards,
Wes

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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Thu Apr 21, 2016 7:32 am

Dear Wes,

6 m/s is the cut-in wind speed of UAE Phase VI rotor (although some tests were run at lower wind speeds). Rated power will not be reached until higher wind speeds.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
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Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Thu May 26, 2016 10:28 pm

Sir, got a new question.. I've read somewhere in this forum (re: NREL Phase VI), about the tip pitch angle (3 degrees) and section pitch angle, (around 4.815 degrees).

I've read from the book of Manwell et al., (2009) that the formula for twist angle is section PA - blade PA at the tip.

The twist angle at the tip from NREL Phase VI is -1.815 degrees and if I will use Manwell's formula, it would be 1.815 degrees and not -1.815 degrees.

Any idea sir why it became this way?

Kind regards,
Wesley

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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Fri May 27, 2016 6:39 am

Dear Wesley,

I'm not sure I really understand your question, but in FAST/AreoDyn, the local angle of the chordline from the rotor plane (theta), is the sum of the blade-pitch angle (theta_p) and the local blade-twist angle (theta_t), the latter of which includes both aerodynamic twist and elastic (live) twist. That is:

theta = theta_p + theta_t

Thus, solving for the local blade-twist angle:

theta_t = theta - theta_p

And using values at the tip:

-1.815 = 3 - 4.815

I hope that helps.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
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Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Sat May 28, 2016 9:37 pm

Jason.Jonkman wrote:Dear Wesley,

I'm not sure I really understand your question, but in FAST/AreoDyn, the local angle of the chordline from the rotor plane (theta), is the sum of the blade-pitch angle (theta_p) and the local blade-twist angle (theta_t), the latter of which includes both aerodynamic twist and elastic (live) twist. That is:

theta = theta_p + theta_t

Thus, solving for the local blade-twist angle:

theta_t = theta - theta_p

And using values at the tip:

-1.815 = 3 - 4.815

I hope that helps.

Best regards,


Sir, thanks for the reply. I think you'd answer my question.

Kind regards,
Wesley :)

Wesley.Miguel
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Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Tue Jun 28, 2016 6:42 am

Jason.Jonkman wrote:Dear Wesley,

I'm not sure I really understand your question, but in FAST/AreoDyn, the local angle of the chordline from the rotor plane (theta), is the sum of the blade-pitch angle (theta_p) and the local blade-twist angle (theta_t), the latter of which includes both aerodynamic twist and elastic (live) twist. That is:

theta = theta_p + theta_t

Thus, solving for the local blade-twist angle:

theta_t = theta - theta_p

And using values at the tip:

-1.815 = 3 - 4.815

I hope that helps.

Best regards,


Sir, there's a literature that it's important to consider aerodynamic, gravitational and centrifugal loads. If the coning angle is zero, do I have to include centrifugal loads?

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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Tue Jul 05, 2016 3:11 pm

Dear Wesley,

I'm not really sure I understand your question, but centrifugal loads are important if you are determining the reaction loads in the blade or calculating blade deformation, regardless of whether the coning angle is zero or not.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
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Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Mon Aug 15, 2016 11:50 pm

Sir, thanks for the answer!

By the way, are there any data concerning the tip deflection of NREL's Phase VI similar to this,
[img]
ae%20data.png
[/img]
Attachments
ae data.png
ae data.png (29.27 KiB) Viewed 5363 times

Jason.Jonkman
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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Tue Aug 16, 2016 8:49 am

Dear Wesley,

Are you asking about real physical data? The blade deflections were not measured in UAE Phase VI experiments.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
Posts: 21
Joined: Sun Apr 17, 2016 12:18 am
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Location: Philippines

Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Tue Aug 16, 2016 9:27 pm

Jason.Jonkman wrote:Dear Wesley,

Are you asking about real physical data? The blade deflections were not measured in UAE Phase VI experiments.

Best regards,


Yes sir.
The real physical data will be used for my aeroelastic validation using NREL's Phase VI.
Any suggestions sir?

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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Wed Aug 17, 2016 7:23 am

Dear Wesley,

Sorry, but I'm not aware of a publicly available dataset that includes physical measurements of blade deflection when the turbine is operating.

We have validated the new capability of FAST v8 for advanced aero-elastically tailored blades, including blade deflection, but this was using experimental data that was proprietary through a collaboration with Siemens: http://www.nrel.gov/docs/fy16osti/65389.pdf.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Wesley.Miguel
Posts: 21
Joined: Sun Apr 17, 2016 12:18 am
Organization: self
Location: Philippines

Re: Help about BEM and NREL's Phase VI

Postby Wesley.Miguel » Thu Sep 01, 2016 10:51 am

Sir,

one question - are there any torsional stiffness/rigidity data concerning NREL Phase VI similar to this?

kind regards,
Wesley
Attachments
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Re: Help about BEM and NREL's Phase VI

Postby Jason.Jonkman » Thu Sep 01, 2016 1:05 pm

Dear Wesley,

Appendix A from the UAE Phase VI report provides some estimates of the torsional stiffness (among other blade structural properties): http://www.nrel.gov/docs/fy02osti/29955.pdf.

However, I did a quick comparison between the blade structural data provided in that report with the data included in the old FAST v7 model of the UAE Phase VI rotor*, and there are certainly some differences. Marshall Buhl of NREL, now retired, developed this model many years ago, and while I don't know the details, I do know he did a bit of manual tuning to ensure the model functioned appropriately.

I hope that helps.

Best regards,

*These are available in the models of Test09 and Test10 in the CertTest directory of the old FAST v7 archive, available here: https://nwtc.nrel.gov/system/files/FAST ... 0d-bjj.exe. Test09 and Test10 in the newer FAST v8 archive are also models of the UAE Phase VI turbine, but the blade torsional stiffness are not specified in the ElastoDyn blade structural input file (available here: https://nwtc.nrel.gov/system/files/FAST ... 0a-bjj.exe).
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


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