Shear Correction Aerodyn Module

Wind & Water Computer-Aided Engineering Software Tools
1

Hello,

We are currently looking for reasons to stabilize Tower Mx loads and found the shear correction option in AeroDyn v15 and would like to understand whether it is ready for practical use.

Our understanding is that this feature is still described as a beta option intended to improve BEM behavior in the presence of wind shear by averaging inflow velocity over a limited azimuthal sector. In our preliminary simulations, activating it leads to a noticeable reduction in load oscillations, as could be seen below:

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Could you please clarify:

  • What is the current stage of development status of this feature?

    • Is it recommended for Design Load Cases at this stage?

  • Why does it produce such a significant difference in loads?

We would appreciate any guidance on whether this option can already be used confidently, or whether it should still be treated only as a trade off study for the moment.

Thank you once again for your time.

Kind regards,

Kepa

2

Dear @Kepa.Cueto,

I would say that the new “shear correction” option introduced in AeroDyn v4 is a step in the right direction, but that we want to do more work in this space to improve the model further. The big reason to add the “sector averaging” was to reduce the amplitude of the normal forces on the rotor in sheared inflow because in various verification/validation projects–such as the IEA Wind Task 47 TURBINIA project–we saw an overprediction of the force amplitude in BEM tools in high shear when compared to predictions from free-vortex wake and high-fidelity CFD. Indeed the sector averaging does reduce the force amplitude, which we liked to see, but it did have an adverse effect on the phase of the forcing and an adverse interaction with dynamic wake (DBEMT) that we did not want to see. We also thought the free-vortex wake solutions we were comparing to also had limitations with respect to how they were handling shear, which could be improved for proper validation of the model.

I hope that helps.

Best regards,

3

Dear Jason,

Thank you very much for the clarification.

From your explanation, I understand that this correction is still an active area of development and validation, so I assume it is still under testing and refinement rather than being considered fully developed.

I would also like to ask whether, in the newer OpenFAST v5.0.0, anything new has been implemented regarding this shear correction approach or its interaction with DBEMT. In particular, I am interested in knowing if there have been any improvements beyond the current sector averaging option.

Best regards,
Kepa

4

Dear @Kepa.Cueto,

No, while we’d like to improve AeroDyn’s shear correction in the future, this model has not improved in v5.0.0.

Best regards,