DOF outputs in FAST V 8

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jonson
Please tell me the corresponding of the outputs “q_DrTr” and “QD_DrTr” (FAST 7) to FAST V8

Sincerely yours

2

Dear @Ali.Elyaakoubi,

These outputs parameters are named the same between FAST v7 and FAST v8. In FAST v8, these output parameters are available through the ElastoDyn module.

Best regards,

3

Thank you so much Mr Jason
Please, what means and what is the corresponding of these outputs in FAST 8/
QD_B1F1, QD_B2F1, QD_B3F1, Q_B1F1, Q_B2F1, Q_B3F1 and QD_GeAz

Sincerely

4

Dear @Ali.Elyaakoubi,

Here are brief descriptions:

  • Q_B#F1 for # = 1,2,3 - displacement of the 1st blade flapwise bending mode degree of freedom for blade #
  • QD_B#F1 for # = 1,2,3 - first time-derivative (velocity) of the 1st blade flapwise bending mode degree of freedom or blade #
  • QD_GeAz - first time-derivative (rotational speed) of the generator-azimuth degree of freedom; note that the generator azimuth state is expressed on the low-speed shaft side of the shaft rather than on the high-speed shaft side of the gearbox.

Much more information is provided in the ElastDyn Theory Manual: 4.2.7. ElastoDyn Users Guide and Theory Manual — OpenFAST v3.5.2 documentation.

Best regards,

5

Thank you so much Mr @Jason.Jonkman
Please what is the difference of ‘QD_GeAz’ to ‘RotSpeed’ and ‘GenSpeed’
Sincerely yours

6

Dear @Ali.Elyaakoubi,

Essentially, GenSpeed is expressed on the high-speed shaft side of the gearbox, so, GenSpeed = QD_GeAz*GBRatio plus the conversion from rad/s (internal units used by QD_GeAz) to rpm (external units used by GenSpeed) that includes a multiplication by 30/pi rpm/(rad/s).

RotSpeed is expressed on the low-speed shaft side of the gearbox, but additionally includes the rotation rate of the drivetrain torsional flexibility (if enabled), i.e., RotSpeed = QD_GeAz + QD_DrTr (plus the conversion from rad/s to rpm).

Best regards,