modal analysis of NREL 5MW wind turbine

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Zimo.Zhu
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Organization: THE HONG KONG POLYTECHNIC UNIVERISTY
Location: Hong Kong

modal analysis of NREL 5MW wind turbine

Postby Zimo.Zhu » Tue May 05, 2020 9:41 pm

Dear all

I have built the finite element model for NREL 5MW wind turbine in ANSYS in order to do dynamic analysis. I use parameters and information provided in https://www.nrel.gov/docs/fy09osti/38060.pdf. The element type I use is beam188 for both tower & blade. After modal analysis, I notice that the natural frequancies I obtained regarding edgewise bending are around 25% higher than the reference value provided, which means my blade model has higher edgewise stiffness than the design value. While other modes arequite accurate. To figure out the reason, I have built a cantilever shell model for the blade according to the information provided by https://prod-ng.sandia.gov/techlib-noau ... 132569.pdf. The natural frequency of 1st edgewise bending is 1.578 in my ANSYS model, while the reference value is 1.06, the error is around 50%. Other modes are accurate with acceptable errors (around 2%). May I know if any other encounters similar probblems? And are there any lab tests for the NREL 5MW wind turbine?

I would be appreciated it if you could reply. Thank you :)

Best regards
Zimo

Jason.Jonkman
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Re: modal analysis of NREL 5MW wind turbine

Postby Jason.Jonkman » Wed May 06, 2020 9:13 am

Dear Zimo,

I'm not aware if others have had similar comments, but I'll let others respond.

Does your ANSYS model include the effect of blade structural pretwist, which couples flap and edge bending? If not, perhaps this could explain the discrepancy?

A full-scale NREL 5-MW turbine has never physically been built, and most physical models at model scale that I'm aware of (for wind tunnel or wave tank testing) use a rigid rotor.

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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