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by Jason.Jonkman
Wed May 12, 2021 4:09 pm
Forum: Computer-Aided Engineering Software Tools
Topic: The frequency component of flapwise
Replies: 11
Views: 3021

Re: The frequency component of flapwise

Dear Feng, Your equation for the natural frequencies above applied to mass and stiffness values written as scalars (or only consider separate terms uncoupled). How are you calculating the natural frequencies with 6x6 matrices? Are you forming the first-order state-space matrix (A) and computing its ...
by Jason.Jonkman
Wed May 12, 2021 3:17 pm
Forum: Computer-Aided Engineering Software Tools
Topic: The frequency component of flapwise
Replies: 11
Views: 3021

Re: The frequency component of flapwise

Dear Feng, Yes, that is the correct full-system mass matrix. Have you now included the coupling between platform DOFs (off-diagonal terms in the matrices, including surge-pitch and sway-roll)--not just for the mass matrix, but also for the added mass matrix and mooring stiffness matrix? Best regards,
by Jason.Jonkman
Wed May 12, 2021 1:52 pm
Forum: Computer-Aided Engineering Software Tools
Topic: The frequency component of flapwise
Replies: 11
Views: 3021

Re: The frequency component of flapwise

Dear Feng, I agree with your numbers, but you seem to be missing three important effects: ⋅ The influence of the platform center of mass (from (0,0,0) on the roll and pitch inertia of platform; ⋅ The influence of the supported wind turbine mass, center of mass, and inertia; and &...
by Jason.Jonkman
Wed May 12, 2021 8:37 am
Forum: General
Topic: FAST.Farm
Replies: 204
Views: 24778

Re: FAST.Farm

Dear Younes, It looks like we responded at the same time; I see now that you can compile in debug mode. It is now telling you which line in the source code is causing the failure (line 137 of SUBROUTINE ComputeLocals() in AWAE.f90 , during the initial call to SUBROUTINE AWAE_CalcOutput()0. It is not...
by Jason.Jonkman
Wed May 12, 2021 6:51 am
Forum: General
Topic: FAST.Farm
Replies: 204
Views: 24778

Re: FAST.Farm

Dear Younes, The Echo variable is a way to debug problems with the formatting of an input file. But you don't seem to have a problem with your input file formats. From my brief look, I'm not seeing any problems with your input settings. I'm not aware of any issue running FAST.Farm with Mod_AmbWind =...
by Jason.Jonkman
Tue May 11, 2021 11:43 am
Forum: Rotor Aerodynamics
Topic: Local angle of attack computation
Replies: 3
Views: 90

Re: Local angle of attack computation

Dear Matteo,

OK, thanks for clarifying.

I have the experience with UAMod = 3 and little experience with UAMod = 2, but in your case, it looks like UAMod = 2 and UAMod = 3 are very similar (some differences are seen in Cd and Cm, but the values are quite small).

Best regards,
by Jason.Jonkman
Tue May 11, 2021 9:36 am
Forum: General
Topic: FAST.Farm
Replies: 204
Views: 24778

Re: FAST.Farm

Dear Jundong, I thought Younes answered your question regarding TwrShadow well. TwrShadow was changed from a TRUE/FALSE flag to an integer input in the dev branch of OpenFAST, i.e.: 0 TwrShadow - Calculate tower influence on wind based on downstream tower shadow (switch) {0=none, 1=Powles model, 2=E...
by Jason.Jonkman
Tue May 11, 2021 9:30 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 364
Views: 77555

Re: FAST theory manual

Sent.
by Jason.Jonkman
Tue May 11, 2021 7:16 am
Forum: Computer-Aided Engineering Software Tools
Topic: VTK output to binary output
Replies: 16
Views: 1426

Re: VTK output to binary output

Dear Tianhui.Liu, Yes, I recommend you use ParaView for the OpenFAST visualization output. You can find some introductory material on using ParaView to view OpenFAST visualization output files here: https://github.com/OpenFAST/r-test/blob/main/glue-codes/openfast/5MW_Land_ModeShapes/vtk-visualizatio...
by Jason.Jonkman
Tue May 11, 2021 6:55 am
Forum: Rotor Aerodynamics
Topic: Printing the axial induction factor in FAST
Replies: 37
Views: 13562

Re: Printing the axial induction factor in FAST

Dear Ricardo, The AeroDyn outputs BbNnVUndx are the wind speeds taken directly from InflowWind, without modification. I expect the values differ from your prescribed value of 10.59 m/s due to a change in coordinate system The AeroDyn outputs BbNnVUndx are expressed in the local blade coordinate syst...
by Jason.Jonkman
Mon May 10, 2021 5:47 pm
Forum: General
Topic: FAST.Farm
Replies: 204
Views: 24778

Re: FAST.Farm

Dear Jundong, Regarding your first question, I've now fixed a small bug in the sc_dll.f90 that would have otherwise caused problems running the super controller compiled with Intel Fortran on Windows. You can find the fix in the following pull request, which I expect will get merged in soon: https:/...
by Jason.Jonkman
Mon May 10, 2021 10:22 am
Forum: Rotor Aerodynamics
Topic: Determing rated wind speed
Replies: 1
Views: 13

Re: Determing rated wind speed

Dear Kumara,

Your first formula is correct, but it is not typically the case that a wind turbine operates at lambda_opt at rated speed. Instead, a wind turbine typically operates with a lambda less than lambda_opt at rated conditions to avoid excessively high tip speeds.

Best regards,
by Jason.Jonkman
Mon May 10, 2021 9:54 am
Forum: Computer-Aided Engineering Software Tools
Topic: Natural frequency DeepCWind and Random Seeds
Replies: 22
Views: 489

Re: Natural frequency DeepCWind and Random Seeds

Dear Andre, Just a few comments: ⋅ I'm not sure what you mean when you present different eigenalysis results at different sea states. OpenFAST will not allow you to linearize when incident waves are enabled; OpenFAST requires that WaveMod = 0 when linearizing, otherwise it would not be pos...
by Jason.Jonkman
Mon May 10, 2021 9:40 am
Forum: Computer-Aided Engineering Software Tools
Topic: Extreme events
Replies: 35
Views: 14654

Re: Extreme events

Dear Vishal, It sounds like your controller is going unstable when you enable pitch control together with the pitch runaway event. Is this a controller NREL has provided or one you implemented yourself? Sounds like you may want to debug why the controller is going unstable. Typically a pitch runaway...
by Jason.Jonkman
Mon May 10, 2021 9:30 am
Forum: Rotor Aerodynamics
Topic: Printing the axial induction factor in FAST
Replies: 37
Views: 13562

Re: Printing the axial induction factor in FAST

Dear Ricardo,

I'm sorry, but I'm not sure I understand your question; please clarify.

Best regards,

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