search

OpenFAST / openfast

Main repository for the NREL-supported OpenFAST whole-turbine and FAST.Farm wind farm simulation codes.
http://openfast.readthedocs.io
Apache License 2.0
688 stars 457 forks source link

Bug report--The difference between the number of output nodes and the number of definition nodes of BeamDyn. #1832

Closed ZL6462 closed 9 months ago

ZL6462 commented 1 year ago

Dear all,

I use the OpenFAST v3.5.0 simulate the aeroelastic performance of the IEA-15MW (download from "https://github.com/IEAWindTask37/IEA-15-240-RWT/tree/master").

The aerodynamic model is DBEM and the structural model is BeamDyn. The number of total blade nodes defined in the BeamDyn.dat is 50, while the number of output nodes in ".out" file is 51. I am confused what results in this issue. image

Thank you for your attention.

jjonkman commented 1 year ago

Dear @ZL6462,

This is not a bug. The BeamDyn model of the IEA Wind 15-MW reference wind turbine uses kp_total = 50, but this is simply used to calculate the reference axis of the blade. Because this model uses trapezoidal quadrature (quadrature = 2), the actual structural analysis nodes are defined where the sectional properties are defined in the table of distributed properties, which are defined along the reference axis. This model uses station_total = 26 with refine = 2 (meaning that there is a node added between each station), resulting in 2*26-1 = 51 structural analysis nodes in this model.

Best regards,

ZL6462 commented 9 months ago

Dear @jjonkman

Sorry for delay. As you mentioned above, This IEA-15MW model uses station_total = 26 with refine = 2, which means that there is a node added between each station. My question is that whether the node is added by linear interpolation. For example, whether the new node between r/R=0.1 and r/R=0.2 is added at the r/R =0.15 position.

Thank for your attention.

jjonkman commented 9 months ago

Dear @ZL6462,

Yes, your understanding is correct.

Best regards,