15MW Reference Turbine - ElastoDyn + BeamDyn Blades

Discuss theory and modeling of wind-turbine structures.

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Sam.Ramsahoye
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15MW Reference Turbine - ElastoDyn + BeamDyn Blades

Postby Sam.Ramsahoye » Thu Apr 30, 2020 12:15 pm

Hi,

For such a large turbine with composite blades and bending/twist coupling, when can one get away with just using ElastoDyn for their simulation? If one is ultimately interested in foundation loads, are differences between the two ultimately smoothed out in macroscopic characteristics of the foundation signals, like standard deviation and damage?

Best,
Sam

Jason.Jonkman
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Re: 15MW Reference Turbine - ElastoDyn + BeamDyn Blades

Postby Jason.Jonkman » Thu Apr 30, 2020 5:12 pm

Hi Sam,

In general, the ElastoDyn blade model does account for many nonlinear terms--e.g., radial shortening (important for centrifugal stiffening), centrifugal, Coriolis, and gyroscopic terms--but the model does have several important simplifying assumptions:
  • Straight when unloaded (but structural pretwist is considered to include coupling between flap and edge)
  • Isotropic material with no offsets in mass or stiffness from the pitch axis
  • Bending only
  • Moderate deflections, not permitting slopes more than about 15 degrees.
BeamDyn is more appropriate when these assumptions are invalid, i.e. for blades with:
  • Build in curvature (when unloaded)
  • Composite-material-induced couplings or offsets of the mass or stiffness form the pitch axis
  • Torsion, shear, and stretching (in addition to bending).
  • Large deflections.
I have not been directly involved in the development of the IEA Wind 15-MW reference turbine , but my understanding is that NREL has focused on the ElastoDyn modeling for now, despite the importance of some of these items.

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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