turbine geometry

Provide feedback, request enhancements, and get help with wind-turbine computer-aided engineering tools.

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Fiona.Luedecke
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Joined: Fri Aug 25, 2017 5:56 am
Organization: University of Stuttgart
Location: Germany

Re: turbine geometry

Postby Fiona.Luedecke » Mon Dec 04, 2017 1:46 am

Dear Jason,

I have a question concerning TwrBsHt.

I have a FAST7 model of an onshore turbine where TowerDraft has a value unequal to zero. Now I want to set up a FAST8 model representing the FAST7 model. But when I set the TwrBsHt to a negative value FAST aborts with the error:
"FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:InflowWind_CalcOutput:CalcOutput:IfW_UniformWind_CalcOutput:GetWindSpeed:Height must not be negative. IfW_UniformWind_CalcOutput: Error calculating the wind speed at position (x, y, z) in the wind-file coordinates"
with z<0
If I don't respect that part of the tower under the ground level, my tower is to short and light weight.
Is there a way to include the part of the tower under the ground level for an onshore wind turbine?

Best regards,
Fiona

Jason.Jonkman
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Location: Boulder, CO
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Re: turbine geometry

Postby Jason.Jonkman » Mon Dec 04, 2017 6:30 am

Dear Fiona,

You should be able to set TowerBsHt to less than zero in FAST v8, as long as you are not modeling a floating offshore wind turbine, which FAST assumes has a rigid platform. The locations of the nodes where wind is calculated in the InflowWind module are not dictated by TowerBsHt, but by the locations of the aerodynamic nodes in AeroDyn. Have you tried to define analysis nodes in AeroDyn to be below the ground?

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

Fiona.Luedecke
Posts: 8
Joined: Fri Aug 25, 2017 5:56 am
Organization: University of Stuttgart
Location: Germany

Re: turbine geometry

Postby Fiona.Luedecke » Mon Dec 04, 2017 7:45 am

Dear Jason,

thank you for your quick answer!

I defined my tower for AeroDyn between 0 and 1 but with your comment I guess that if I set TwrBsHt to a negative value the tower length he uses as reference is the total length (TowerHt +TwrBsHt) so then the TwrHtFr=0 would be under the ground and I would need to start with a value higher than 0.

Am I guessing right?

Best regards,
Fiona

Fiona.Luedecke
Posts: 8
Joined: Fri Aug 25, 2017 5:56 am
Organization: University of Stuttgart
Location: Germany

Re: turbine geometry

Postby Fiona.Luedecke » Mon Dec 04, 2017 7:56 am

Dear Jason,

I just tried to adapt the scaling in the AeroDyn-Tower.dat, but that doesn't help. The error stays the same. What analysis nodes do you meen?

Best regards,
Fiona

Jason.Jonkman
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Location: Boulder, CO
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Re: turbine geometry

Postby Jason.Jonkman » Mon Dec 04, 2017 8:59 am

Dear Fiona,

Ah;I thought that you were using AeroDyn v15, but you are actually using AeroDyn v14.

In AeroDyn v14, the tower discretization in ElastoDyn is used by AeroDyn, so, you cannot extend the tower in ElastoDyn below the ground if you've enabled tower aerodynamics. However, in AeroDyn v15 the aerodynamic nodes are independent from those in ElastoDyn, allowing you to extend the tower in ElastoDyn below the ground. So, you can either upgrade from AeroDyn v14 to AeroDyn v15, disable tower aerodynamics in AeroDyn v14, or don't set TowerBsHt in ElastoDyn negative.

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

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

Re: turbine geometry

Postby Satish.Jawalageri » Mon Feb 08, 2021 4:00 am

Dear Jason,

If I want to change the tower and blade geometry (Increasing/decreasing the lengths) of NREL 5MW turbine. Which input files needs to be modified other than elastadyn_tower file or is it allowed to change these geometry.

Thanks,
Satish J

Jason.Jonkman
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Location: Boulder, CO
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Re: turbine geometry

Postby Jason.Jonkman » Mon Feb 08, 2021 6:49 am

Dear Satish,

To change the length of the tower or blade, you'd have to change the geometry in the ElastoDyn primary input file, as well as the mass and stiffness in the ElastoDyn tower and blade files. You'd also have to change the tower and blade geometry defined in the AeroDyn primary and AeroDyn blade files. Finally, you'd likely have to change how the wind data and wind profile are defined in InflowWind and TurbSim.

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

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

Re: turbine geometry

Postby Satish.Jawalageri » Mon Feb 08, 2021 8:36 am

Dear Jason,

Thanks for your reply.

I have changed as suggested above and my rotor diameter of 112m and hub radius of 1.3m where hub height above the MSL is 80m. I have interpolated the tower and blade lengths according to my lengths. I have attached related input files, could you please advice if anything needs to be changed.

Thanks,
Satish J
Attachments
NRELOffshrBsline5MW_OC3Monopile_reduced_geometry.zip
(12.68 KiB) Downloaded 21 times

Jason.Jonkman
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Location: Boulder, CO
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Re: turbine geometry

Postby Jason.Jonkman » Mon Feb 08, 2021 9:15 am

Dear Satish,

It looks like you changed the geometry (tower and blade lengths) correctly in all files. The big thing I noticed, though, is that while you changed the member lengths, you didn't change an of the member distributed properties, such cross-sectional mass and stiffness or blade chord. This means that the blade and tower masses will decrease, natural frequencies will increase, and the rotor solidity will increase. These are not necessarily optimal turbine design changes.

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

Satish.Jawalageri
Posts: 117
Joined: Sun May 31, 2020 4:57 am
Organization: University College Dublin
Location: Ireland

Re: turbine geometry

Postby Satish.Jawalageri » Mon Feb 08, 2021 10:34 am

Dear Jason,

Thanks for your reply.

Could I please know in which files I need to change the mass/stiffness as there is unit mass/length in elastodyn_tower. Is the formula below is correct to calculate blade chord?

Thanks,
Satish J
Attachments
Capture1.PNG
Capture1.PNG (60.31 KiB) Viewed 442 times

Jason.Jonkman
Posts: 5778
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: turbine geometry

Postby Jason.Jonkman » Mon Feb 08, 2021 11:00 am

Dear Satish,

Yes, the cross-sectional (per unit length) values of the tower mass and stiffness are specified within the ElastoDyn tower file. Likewise, the cross-sectional values of the blade mass and stiffness are specified within the ElastoDyn blade file(s).

I'm not familiar with the equation you state for the blade chord.

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


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