Thrust coefficient in turbine input file

[Marcodep23]

Dear all,

I am working with FLORIS (v3.5, with emgauss model) and FAST.Farm trying to achieve the similar results for a really simplified load case: 2 turbines in line (IEA 15MW - Bottom Fixed) spaced by 5D, with an input steady and uniform wind field of 10 m/s.

To build the turbine input file of FLORIS, I extracted the Ct and Cp values from openfast with a step wind input simulation. However I noticed that the Ct values that I obtained are different from those reported in "IEA-15-240-RWT_tabular.xlsx" present in the path "https://github.com/IEAWindTask37/IEA-15-240-RWT/tree/master/Documentation" (see figure).

Additionally, I have observed that the results in FLORIS, when using the Ct values from the "IEA-15-240-RWT_tabular.xlsx" file, closely match those from FAST.Farm in terms of power and averaged rotor wind speed of the downstream turbine. However, when I use the Ct values calculated by myself, the results in FLORIS differ significantly. This leads me to believe I am making a mistake, but I am unsure what it might be. I am extracting the variable "RtAeroCt/RtFldCt" from OpenFAST.

Hoping to get some help,
Regards,

Marco

[misi9170]

Hi Marco,

If I'm understanding your issue correctly, the Ct data that you are getting from your OpenFAST simulations (extracting "RtAeroCt/RtFldCt") is not a great match to the data reported at "https://github.com/IEAWindTask37/IEA-15-240-RWT/tree/master/Documentation" ---is that correct?

I'm not sure that I can help you here, since we simply implement the Ct curves reported by the OpenFAST team at https://github.com/IEAWindTask37 in FLORIS (we made a dedicated effort to improve this coupling for FLORIS v4, see #771, although the IEA 15MW curves did not change much during this process). However, perhaps you could ask on the OpenFAST discussions for the process that is taken to produce the curves in the IEAWindTask37 repository?

Feel free to tag me (@misi9170) if you do open a discussion there!

Thanks, and sorry to not be very helpful,
Misha

[rafmudaf]

Heads up the link to OpenFAST discussions is https://github.com/openfast/openfast/discussions

It's incorrect above, probably just a copy/paste error

[misi9170]

Thanks @rafmudaf --- now corrected above!