CONING ANGLE

[ILDENIEL]

Hi all, I have a question regarding the power of a turbine modeled starting from the 5MW Baseline (OpenFAST v3.5.2) but:

• rigid (both blades and tower)
• no tower influence (TwrPotent = 0)
• tilt = 0

• yaw = 0

  A turbine with coning = 2.5° produces an average aerodynamic power higher than the case with coming = 0. What could be the reasons for this behaviour?

[ILDENIEL]

The "REF" has tilt = coning = yaw = 0 The "δ = 2.5" case is the one with a precone of 2.5° Could it be due to the Angle of Attack?

[ILDENIEL]

Dear @jjonkman, do you have any suggestions?

[jjonkman]

Dear @ILDENIEL,

I'm not fully sure. Are the cases without shear?

@ebranlard has been making several improvements to the BEM implementation of AeroDyn to better support cone, blade deflection, skew, and shear. The following pull requests are likely of interest to you, especially #1509: https://github.com/OpenFAST/openfast/pull/1283 https://github.com/OpenFAST/openfast/pull/1509 https://github.com/OpenFAST/openfast/pull/1679 https://github.com/OpenFAST/openfast/pull/1909

Currently, the various new BEM options are a bit "hidden", but these will become more user-accessible with #1909.

Best regards,

[ILDENIEL]

Dear @jjonkman, the incoming wind speed has been modeled constant in time and uniform in space (V = 11.4m/s), so the power law exponent of the wind shear distribution has been set to 0.

[ILDENIEL]

Is it possible that my results are not 100% correct because of this bug? In this case, how can I cite all the issues encountered in OpenFAST and, more importantly, your fundamental contribution ( such as https://github.com/OpenFAST/openfast/issues/2044)?

[jjonkman]

Dear @ILDENIEL,

I wouldn't call AeroDyn before @ebranlard's recent improvements "buggy", but @ebranlard's changes should improve the accuracy of the aerodynamic predictions for cases with cone, blade curvature, skew, and shear.

I'm not sure I understand your question about "citing"?

Best regards,

[ILDENIEL]

Dear @jjonkman I mean that I would like to mention your help and contribution, which helped me a lot to understand some topics regarding OpenFAST by citing the issue section in my work.

Best regards,

[jjonkman]

Dear @ILDENIEL,

I don't have specific guidance for mentioning NREL (or my) support, but listing that support in the Acknowledgements section of a publication is appreciated. And you can always add citations or footnotes that direct link to websites such as this OpenFAST repository.

Best regards,

[ILDENIEL]

Dear @jjonkman, thanks again, I will mention the OpenFAST main repository. I will further investigate the coning effect with the features of the new BEM in the near future. Best regards