Recommended or default UA constants per UAMod

Wind & Water Airfoils
1

Dear OpenFAST team,

I’m currently reviewing the implementation of the Beddoes–Leishman unsteady aerodynamic model in AeroDyn, comparing it against formulations and applications such as:

  • T.S. Beddoes, Practical Computation of Unsteady Lift
  • R. Pereira, G. Schepers, M. de Pavel, Validation of the Beddoes–Leishman Dynamic Stall Model for HAWTs using MEXICO data
  • J.G. Leishman, Principles of Helicopter Aerodynamics

In these documents, I found several of the parameters recommended by openfast for constants. I also found that GH Bladed explicitly recommends default values for these constants for different Unsteady Aerodynamic Models, as shown below:

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So my question is the next one:

Could you please clarify if the same default constant values are recommended across all UAMod versions? Or are there any recommended constant sets specific to each UAMod?

Thank you once again for your time,

Kepa

2

Hi,

The values you report seems correct. The differences in the coefficients stems from the difference between the Kussner (sum of coeffs=1, functions starts at 0) and the Wagner function (sum of coeffs =0.5, function starts at 0.5). The Wagner function was derived for a change in angle of attack, while the Kussner function is for a vertical gusts.

I hope that helps,

Emmanuel

3

Hi Emmanuel, thank you for your response.

As far as I understand, OpenFAST’s AeroDyn uses Kussner type coefficients by default:

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While Bladed commonly employ a Wagner type one so:

  • For turbine simulations with active UAMod, which formulation do you recommend in OpenFAST: Kussner or Wagner? If recommendations differ by UAMod, could you share them please?

Thank you and kind regards,

Kepa

4

Hi,

I do not have a recommendation at the moment :slightly_smiling_face: I would stick to the values listed in the input file of OpenFAST as these are the ones currently used by the community. The values are left as parameters for users to calibrate if needed. I am working on some of these calibrations, I can let you know if I find anything!

Emmanuel

1 Like
5

Thank you very much, Emmanuel. I would be very grateful if you could let me know.

Kind regards,

Kepa