Turbine tilt angle GCH model

[LuukSengers]

Hi there,

Previously I used v2.2.2, in which tilt_angle was a standard parameters in the .json-file (never tested it though), but in gch.yaml and nrel_5MW.yaml in v3.0.1 this parameters seems to be no longer present. I did find it hardcoded in Gauss.py L146. Would this be the correct (or only) position to change this parameter, or am I missing something?
Just as a check: NREL5MW has a shaft tilt of -5 deg in FAST. Is it correct that this shaft tilt corresponds to the tilt_angle I mentioned here?

Lastly: I'm studying wake steering for single wake cases only. Would you recommend to work with GCH or CC?

Many thanks in advance!
Luuk

[rafmudaf]

Hi @LuukSengers

The tilt angle in earlier versions of FLORIS are for tilt control and primarily used to model wake steering in the vertical direction.

NREL5MW has a shaft tilt of -5 deg in FAST. Is it correct that this shaft tilt corresponds to the tilt_angle I mentioned here?

The OpenFAST NREL 5MW model does specify a shaft tilt, but the performance tables (Cp vs wind speed, Ct vs wind speed) that are used in the FLORIS NREL 5MW model are created considering the upward tilt in the OpenFAST definition. Since the tilt in the turbine definition is already captured, it would be double-counted if you change the tilt angle in the Gauss deflection model.

Would this be the correct (or only) position to change this parameter

During the v3 effort, we intentionally left tilt-control out of the models. You may have noticed the #TODO in the line you referenced in the Gauss deflection model. We may add this feature again in a future release.

I hope this resolves your question, but please let us know if something isn't clear.

[LuukSengers]

Hi @rafmudaf

Appreciate you coming back to me so quickly!

One follow up question:
I'm mainly looking at the wind field / wake at a few rotor diameters downstream, not necessarily the power generated by the turbine. In a comparison between field measurements and LES (+ ADMR of NREL 5MW with tilt = 0deg) I found a vertical wake displacement.
I just want to make sure I use the "most correct" FLORIS setup tuning it with this field data.

With this background info, would you recommend me to keep using tilt_angle = 0, or would you suggest another setup / changes to the code?

Thanks again!
Luuk

[rafmudaf]

Well, its a good question and I'm not sure I can fully answer, but @bayc or @paulf81 probably can.

Since the NREL 5MW performance in FLORIS comes from the model with shaft tilt included, I expect that the FLORIS wake profile and the OpenFAST (via FAST.Farm) wake would be similar. Your LES simulation probably has a few more parameters available that could impact the wake.

@paulf81 do you have any insight into this? I think there's two things: comparing FLORIS results with LES and then comparing LES+ADMR with field measurements.