15MW VolturnUS-S Tower Design

Hi all,

I am aiming to perform experiments modifying the tower of the VolturnUS-S in WISDEM/WEIS. Within the definition document, the tower is tapered like so:

However, within the input .yaml file for the VolturnUS-S in WISDEM, the tower diameter is set to uniform 10m until the final node, whose diameter is 6.5m.

The thicknesses are also different in the .yaml file than within the reference document

When running WISDEM with these settings, the tower file produced gives the same “Distributed Tower Properties” as the tower file provided for the OpenFAST model of the turbine (indicating that the default OpenFAST tower file is using the same tower diameter and thickness profile as in the WISDEM .yaml file) but different Tower mode shapes, which then impacts upon the natural frequency of the tower

My questions are:

  • Why is the tower design of the VolturnUS-S tower within OpenFAST/WISDEM different to that of the reference document (i.e. not tapered with a different thickness profile)?
  • Why are the tower mode shapes calculated from WISDEM and written to the ElastoDyn_Tower file different to those of the defaults OpenFAST ElastoDyn_Tower file and how might I be able to get them to be the same?

Many thanks,


1 Like

Hello Andrew,
the design of the tower of the floating IEA-15 suffered from resonance and had to be stiffened up. This is documented here Frequently Asked Questions (FAQ) · IEAWindTask37/IEA-15-240-RWT Wiki · GitHub (although not much data is provided). Overall I’d recommend sticking to the new tower design and discard the data from the tech report. Regarding your second question, the mode shapes between the two files might be very close and differences might come from differences in the drivetrain component masses, where WISDEM is not always 100% consistent. I’d again stick to the values provided on GitHub.
I hope this helps.
best regards,

Hi Pietro,

Thank you for the reply, that clears things up so I’ll stick with the GitHub values.

Kind regards,