How OpenFAST calculate the pitching moment at the blade root? #2521
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Dear all. I would like to understand how the "RootMzb1" output, which represents the "Blade 1 pitching moment at the blade root," is calculated in OpenFAST. Could you please share if there is a specific equation or methodology used for this calculation? Thank you so much. |
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Replies: 1 comment 3 replies
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Dear @sstonee2024, See a similar question asked and answered in the following OpenFAST issue: #1916. Best regards, |
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Thank you for your prompt reply, Mr. Jonkman. I reviewed the post you mentioned and found that the equation discussed there relates to the blade-root bending moments, not the pitching moment that I am seeking. Additionally, I examined the source file ElastoDyn.f90 and discovered only two references to the pitching moment. I attempted to understand the code within ElastoDyn.f90, but it contains more than 10,000 lines, which is overwhelming for me. I recognize that I should dig deeper into that file, but I find it quite challenging. Could you please do me a favor by providing the equation for the pitching moment in OpenFAST? I don't know if my request is too much, I apologize if I bothered you. Thank you very much. |
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Dear @sstonee2024, The equation summarized in the issue I linked to above applies to both the blade-root bending moments and the pitching moment. That is, once the integral along the blade of the applied aerodynamic pitching moments + ( radial vector ) x ( applied aerodynamic forces + gravitation forces - inertia forces ) is calculated, the resulting moment vector is projected along the x, y, and z axes of the blade-root coordinate system to calculate the bending moments about x and y and the pitching moment about z. For the mathematical details, see the ElastoDyn Theory Manual on readthedocs: https://openfast.readthedocs.io/en/main/source/user/elastodyn/index.html. The FASTLoads.doc contains the mathematical details for the blade-root loads, although you'd need the review the documents earlier in the list to understand the nomenclature. Best regards, |
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Dear @jjonkman, Thank you so much for your quick reply, Mr. Jonkman. It helped me a lot. Truly appreciate it. Wish you everything going well. Best regards, |
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Dear @sstonee2024,
The equation summarized in the issue I linked to above applies to both the blade-root bending moments and the pitching moment. That is, once the integral along the blade of the applied aerodynamic pitching moments + ( radial vector ) x ( applied aerodynamic forces + gravitation forces - inertia forces ) is calculated, the resulting moment vector is projected along the x, y, and z axes of the blade-root coordinate system to calculate the bending moments about x and y and the pitching moment about z.
For the mathematical details, see the ElastoDyn Theory Manual on readthedocs: https://openfast.readthedocs.io/en/main/source/user/elastodyn/index.html. The FASTLoads.doc cont…