OpenFAST development

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jason,

I find the OutListParameters.xlsx file located in “OpenFAST\openfast(master)\modules-local\aerodyn\src” lags behind the released version of AeroDyn_IO.f90, since there are some new channels (e.g. B3N9SgCav = 1167, etc.) that have been defined in AeroDyn_IO.f90 but not yet in OutListParameters.xlsx_AerodDyn. Could you update it to the consistent version of AeroDyn_IO.f90 in the OpenFAST master branch or just temporarily upload it here? Thanks.

Best regards,
Yingyi Liu

2

Dear Yingyi.Liu,

I’ve sent an e-mail about this to Rafael Mudafort and Cc’d you.

Best regards,

3

Dear Jason,

My modification of the OpenFAST code is to add a functionality of the tower lift load for an airfoil-shaped tower, as we communicated many times before.

My general methodology of the modification is to find where TwrCd (tower drag load) locates and then modify the places by adding TwrCl (tower lift load).

I have modified almost all the distinct places regarding this issue, e.g., array definition, initiation, calculation, etc.

But I also noticed that there are some places which involve TwrCd, e.g., the tower influence/shadow model.

In SUBROUTINE TwrInfl_NearestLine2Element of AeroDyn.f90, there exists:
…
TwrDiam = elem_position2p%TwrDiam(n1) + elem_positionp%TwrDiam(n2)
TwrCd = elem_position2p%TwrCd( n1) + elem_positionp%TwrCd( n2)
…

And in SUBROUTINE TwrInfl_NearestPoint of AeroDyn.f90, there exists:
…
TwrDiam = p%TwrDiam(n1)
TwrCd = p%TwrCd( n1)
…

Should I modify these two places as well? or in another word, does the tower lift load affect the tower influence/shadow model as well? To what extent the tower lift load affects, negligible?

If it really affects, could you tell me where I can find the theory of the tower influence/shadow model built in OpenFAST?

Thanks.

Best regards,
Yingyi Liu

4

Dear Yingyi.Liu,

The existing implementation of the tower-influence and -shadow models in AeroDyn v15 assumes that the tower is cylindrical. This is one reason why we never implemented aerodynamic lift forces on the tower. I’m not aware of similar tower-influence and -shadow models that are applicable to airfoil-shaped towers. The existing tower-influence and -shadow models are documented in the 2005 AeroDyn Theory Manual by Moriarty and Hansen: nwtc.nrel.gov/system/files/AD_Theory.pdf.

Please note, though, that there are two typos in the “Tower Influence” section in this manual:

  • The “1” in Eqs. [111] and [117] should not be there because the disturbance should be based on U_inf at the tower and the undisturbed wind (the 1) should be based on local U_inf, which is likely different.
  • The 1st term on the right-hand side of [112] should have a negative sign out front.

Best regards,