Generator power of a simulated IEA-15MW significantly higher than expected

[delloiacono]

Hi,

I simulated a floating IEA-15MW wind farm both in AMR-Wind and FAST.Farm.
I noticed that the generator power (figure attached) of the upwind turbine calculated by AMR-Wind/OpenFAST is unexpectedly higher, wrt to FAST.Farm as well as the definition of the turbine itself. I would expect less power, as in AMR-Wind I have induction upstream of the rotor and thus a lower wind speed (figure attached).

So, as a test case I also simulated one single bottom-fixed turbine in uniform flow, and I compared the results with an openfast simulation with InflowWind. Basically, I noticed the same behavior. My settings for this small case are attached.

Thank you in advance for your help.

uniform_inflow_test.zip

[marchdf]

Hi, thanks for reaching out! Before getting too deep into things, have you looked at our documentation on this subject: https://exawind.github.io/amr-wind/walkthrough/calibration.html. Also, might be worth looking at: #1534

[delloiacono]

Hi, I looked at the calibration studies both in the documentation and in the article [https://onlinelibrary.wiley.com/doi/pdf/10.1002/we.70010] and I also read the discussion at #1534.
I conducted a similar test on a bottom-fixed IEA-15MW in uniform inflow and no ground effect, represented with an ADM. The background grid size is 20 m, while near the turbine is 5 m. I used 60 actuator points along the blade and several values for the epsilon parameter.
I noticed that with the "rule-of-thumb" value (eps=2*dx=10 m) I have significantly higher generator power and torque, as well rotor speed and thrust, with respect to what expected. I can match the results of a standalone OpenFAST simulation only setting eps=3, but with this value the wake behind the turbine does not evolve properly, as expected since the spreading parameter is even smaller than the grid size.
You can find all the files of the setup and the results in the attached folder.
I don't know if I have some problems in the AMR-Wind or the OpenFAST input files, I hope you can help me fix this problem.

Thanks in advance for your help!

ADM_test.zip

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