Eigenvalue Analysis of OC3 Hywind

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Eigenvalue Analysis of OC3 Hywind

Postby Danupon.Subanapong » Thu Feb 07, 2019 9:23 am

I am working with modelling of FOWT in FAST v.8. In ElastoDyn input, the mode shape of each tower modes is necessary to be inputted. I used BModes to derive those mode shapes. However, before I use it to model 2MW FOWT I checked the values of mode shapes used in ElastoDyn of OC3 Hywind project (coefficients of six order polynomial fitted values) and I compare with the one I obtained from BModes (obtained from OC3 Hywind's Bmodes model) and fitted by using polynomial equation. I found that the values of 1st tower fore-aft and side-side obtained from BModes give good agreement with FAST default values in OC3 Hywind FAST demo file, but the values of mode shapes of 2nd fore-aft and side-side obtained by BModes are differnt from FAST ElastoDyn input default values. So, I am wondering if BModes can be used to derive mode shapes for FAST? Could you please give me some suggestion on this?
Thank you in advance
Danupon Subanapong

Posts: 5170
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO

Re: Eigenvalue Analysis of OC3 Hywind

Postby Jason.Jonkman » Thu Feb 07, 2019 9:45 am

Dear Danupon,

This question has been asked and answered on this forum before--e.g. see the posts dated May 07-08, 2018 in the following forum topic: viewtopic.php?f=3&t=1945&p=11222.

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

National Renewable Energy Laboratory (NREL)
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