How to apply icedyn to floating turbines in FAST

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Tianhui.Liu
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How to apply icedyn to floating turbines in FAST

Postby Tianhui.Liu » Mon Mar 01, 2021 7:04 pm

Hi all,

I am currently using glue-code in openfast for debugging calculations. Take 5MW_OC3Spar as an example, I can call icedyn in the setup file, but I need subdyn which is not contained in the 5MW_OC3Spar folder . How do I get the subdyn file, do I need to design the modeling for this?

Kind regards,
Liu.

Jason.Jonkman
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Re: How to apply icedyn to floating turbines in FAST

Postby Jason.Jonkman » Tue Mar 02, 2021 12:56 pm

Dear Liu,

Until a recent pull request into the dev branch of OpenFAST, SubDyn was only applicable to fixed-bottom, not floating systems. However, the following pull request allows SubDyn to be enabled for floating offshore wind turbines, which is applicable to modeling floating substructure flexibility and the calculation of internal member-level loads: https://github.com/OpenFAST/openfast/pull/537. That said, none of our sample floating offshore wind OpenFAST models, like the OC3-Hywind spar, have been updated to include SubDyn and floater flexibility; this limitation has been raised in the following r-test issue: https://github.com/OpenFAST/r-test/issues/39. (The testing we have done has been for floaters that contain proprietary information that cannot be shared publicly.) If you wish to introduce a SubDyn model of the OC3-Hywind spar, you'll have to switch to the dev branch of OpenFAST and you'll likely have to make your own assumptions about the structural characteristics of the spar (as these details were never published).

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

Rui.Hao
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Re: How to apply icedyn to floating turbines in FAST

Postby Rui.Hao » Fri Mar 05, 2021 10:30 pm

Dear Jason

What is the difference between the 'RotSpeed' and the 'LSSGagVxa' ?

Jason.Jonkman
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Re: How to apply icedyn to floating turbines in FAST

Postby Jason.Jonkman » Mon Mar 08, 2021 9:11 am

Dear Rui.Hao,

ElastoDyn output RotSpeed is equivalent to the ElastoDyn output LSSTipVxa (LSSTipVxa and RotSpeed are two different names for the same output), which is the rotational speed of the low-speed shaft on the rotor side of the shaft. LSSGagVxa is similar, but LSSGagVxa is the rotation speed of the low-speed shaft on the gearbox side of the shaft. The difference between these two is the flexibility of the drivetrain, if enabled (DrTrDOF = TRUE). If the drivetrain flexibility is disabled (DrTrDOF = FALSE), then LSSGagVxa = LSSTipVxa = RotSpeed.

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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