Need to confirm correct settings for including Tower shadow

[PaulKSmith]

Hello everyone,

I want to understand the effect of tower shadow and tower passing in low speed shaft forces better. So, I was checking with NREL 5MW case. I kept the TwrShadow to 1=Powles model in AeroDyn module, while running the steady wind case. I do not see any visible difference with and without it. Is this correct or am I setting something incorrect?

Also do I need to include TwrPotent or TwrAero as well?
I am also considering checking with turbulence. In that case shall I need to choose any specific settings for tower effects?

Regards,

[jjonkman]

Dear @PaulKSmith,

In AeroDyn, the TwrShadow models are meant for wake behind a tower for downwind rotors. Given that the NREL 5-MW baseline wind turbine has an upwind rotor, I would not expect TwrShadow to have an effect. It is the tower influence model that you should enable to capture influence of the upstream tower "bow" wake" on the upwind rotor, e.g,, by setting TwrPotent = 1.

Best regards,

[PaulKSmith]

Dear @jjonkman,

Thank you for the insight. Is there any discussion related to difference between TwrPotent = 1 or 2 ? Or can I choose the same settings with other class of wind turbines? I am just interested in the realistic load calculations on the low speed shaft.

Regards,

[jjonkman]

Dear @PaulKSmith,

TwrPotent = 2 incorporates a drag correction to the baseline potential flow model of TwrPotent = 1, as proposed by Bak. The two models are described in the AeroDyn Theory Manual from 2005: https://www.nrel.gov/docs/libraries/wind-docs/ad-theory.pdf?sfvrsn=9fed28e8_1. Current implementation details are documented in: https://openfast.readthedocs.io/en/main/_downloads/16e90183fbf96337d383d6bd287c9aca/AeroDynMesh_Rev4.docx.

Best regards,