Each parameter of "Full_frequencies" for eigenfrequencies in the SubDyn summary file

[DaraeShin]

Dear all,

I woud like to know in Openfast.
I can only see the number values of "Full_frequencies" in #eigenfrequencies.

May I know the parameter corresponding to the number values in #eigenfrequencies?

[jjonkman]

@DaraeShin,

I'm not sure I really understand what you are asking. What do you mean by "the parameter corresponding to the number of values"? Please clarify.

Best regards,

[DaraeShin]

@jjonkman,

I want to know the definition of a number corresponding to #1X54 (metrix).

Thanks, @jjonkman

[jjonkman]

@DaraeShin,

This just means that there are 54 full-system eigenfrequencies, so, the row vector has 54 elements.

Best regards,

[DaraeShin]

@jjonkman,
Thank you for your answer.

How can I get the natural frequency[Hz] below in Full-system Eigenanalysis?

• 1st Tower Fore-Atf
• 1st Tower Side-to-Side
• 1st Drivetrain Torsion
• 1st Blade Collective Flap
• 1st Blade Asymmetric Flapwise Pitch
• 1st Blade Asymmetric Flapwise Yaw
• 1st Blade Asymmetric Edgewise Pitch
• 1st Blade Asymmetric Edgewise Yaw
• 2nd Tower Fore-Atf
• 2nd Tower Side-to-Side
• 2nd Blade Collective Flap
• 2nd Blade Asymmetric Flapwise Pitch
• 2nd Blade Asymmetric Flapwise Yaw

[jjonkman]

Dear @DaraeShin,

SubDyn is just a model of the substructure. So, the "full-system eigenfrequencies" reported in the SubDyn summary file are just for the substructure. It looks like you are after the natural frequencies of the full wind turbine system (blades + drivetrain + nacelle+ tower + substructure). These cannot be output from SubDyn. Calculating these requires the use of the full-system linearization functionality of OpenFAST, as has been discussed before on this issues page (e.g., here: #480), as well as many times on our forum: https://wind.nrel.gov/forum/wind/.

Best regards,