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by Jason.Jonkman
Thu Jun 25, 2020 1:25 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Start-up of NREL 5MW
Replies: 4
Views: 95

Re: Start-up of NREL 5MW

Dear Paul, My guess is the problem is a related to lack of proper initial conditions that keeps the controller from being initialized properly. When TPCOn = 0, you likely give the simulation reasonable initial conditions of rotor speed and blade-pitch angle, but when TPCOn = 5, the rotor likely over...
by Jason.Jonkman
Thu Jun 25, 2020 1:09 pm
Forum: Computer-Aided Engineering Software Tools
Topic: standalone YawDyn
Replies: 2
Views: 48

Re: standalone YawDyn

Dear Mohamed,

Wow, I haven't had a question about YawDyn in a long time. But you can find the newest archive (but still old, from 2005) here: https://drive.google.com/drive/folders/ ... sp=sharing.

Best regards,
by Jason.Jonkman
Thu Jun 25, 2020 8:58 am
Forum: Computer-Aided Engineering Software Tools
Topic: BModes and PreComp
Replies: 3
Views: 110

Re: BModes and PreComp

Dear Balazs,

Hopefully BModes v3.00.00 can use the same version of the NWTC Library that I shared with you in my previous post.

Best regards,
by Jason.Jonkman
Thu Jun 25, 2020 7:59 am
Forum: Controls
Topic: Pitch angle goes to 90º
Replies: 2
Views: 102

Re: Pitch angle goes to 90º

Dear Iñigo, There is nothing controls-related that is built-in within FAST v7 that is outside of the user-specified control settings. There are override pitch maneuver settings and settings to disable the generator that are user-specified. What control settings have you defined in the FAST v7 input ...
by Jason.Jonkman
Thu Jun 25, 2020 7:09 am
Forum: Structural Analysis
Topic: Processing OpenFast linearization output
Replies: 56
Views: 1615

Re: Processing OpenFast linearization output

Dear Srinivasa, Which sample OpenFAST model are you using (can you send me a link to the file on github)? The test I see uses ElastoDyn: https://github.com/OpenFAST/r-test/blob/pullrequest/bjonkman-linear/glue-codes/openfast/5MW_Land_ModeShapes/5MW_Land_ModeShapes.fst. I'm sure TMax = 10000 is more ...
by Jason.Jonkman
Thu Jun 25, 2020 6:47 am
Forum: Computer-Aided Engineering Software Tools
Topic: Tendon failure in FAST modeling
Replies: 47
Views: 10106

Re: Tendon failure in FAST modeling

Dear Abhinay, I'm glad that you've now successfully compiled your updated source code. I'm not sure what type of floater this is (a semisubmersible?), and perhaps Matt can comment further, but assuming the mooring lines are centenaries, I would imagine the mean tensions in the remaining lines after ...
by Jason.Jonkman
Thu Jun 25, 2020 6:40 am
Forum: Structural Analysis
Topic: hydrodynamic model for semisubmersible FOWT
Replies: 10
Views: 2266

Re: hydrodynamic model for semisubmersible FOWT

Dear Yajun,

The platform mass moments of inertia in the ElastoDyn structural-dynamics module of FAST / OpenFAST (PtfmRIner, PtfmPIner, PtfmYIner) are all specified bout the platform center of mass location (PtfmCMxt, PtfmCMyt, PtfmCMzt).

Best regards,
by Jason.Jonkman
Wed Jun 24, 2020 8:52 am
Forum: Structural Analysis
Topic: Processing OpenFast linearization output
Replies: 56
Views: 1615

Re: Processing OpenFast linearization output

Dear Srinivasa, Here are my answers to your questions: 1. The use of BeamDyn generally requires a small time step; DT=0.001 s is what NREL decided was appropriate for a numerically converged solution. You won't be able to increase this without disabling model features (e.g., disabling degrees of fre...
by Jason.Jonkman
Tue Jun 23, 2020 5:22 pm
Forum: Structural Analysis
Topic: Processing OpenFast linearization output
Replies: 56
Views: 1615

Re: Processing OpenFast linearization output

Dear Srinivasa, Here are my answers to your questions: 1. The model 5MW_Land_BD_Linear.fst is not set up correctly to generate a Campbell diagram; this test was simplified for testing the compiled code, not producing useful results. For example, to generate a proper Campbell diagram, you'll need to ...
by Jason.Jonkman
Tue Jun 23, 2020 2:11 pm
Forum: General
Topic: Current and Wave simulation
Replies: 9
Views: 2116

Re: Current and Wave simulation

Dear Dhaneesh, Here are my answers to your questions: 1. The strip-theory formulation of FAST's HydroDyn hydrodynamics module uses the relative form of Morison equation, with extensions for end effects, tapered members, buoyancy, etc. The Froude-Krylov force is the integration of the undisturbed pre...
by Jason.Jonkman
Tue Jun 23, 2020 8:00 am
Forum: Structural Analysis
Topic: Campbell diagram for 5MW turbine rotor
Replies: 44
Views: 22146

Re: Campbell diagram for 5MW turbine rotor

Dear Srinivasa,

This is simply a naming convention. By "regressive", I mean the asymmetric mode that reduces in frequency with increasing rotor speed. By "progressive", I mean the asymmetric mode that increases in frequency with increasing rotor speed.

Best regards,
by Jason.Jonkman
Mon Jun 22, 2020 6:57 pm
Forum: Inflow Turbulence
Topic: Step wind change input
Replies: 5
Views: 4814

Re: Step wind change input

Dear Jing, The uniform wind data files can be created by hand or with simple scripts. As I announced here: https://wind.nrel.gov/forum/wind/viewtopic.php?f=38&t=1001, the http://wind.nrel.gov/public/jjonkman/ site has also been taken down. I've now shared the InflowWind User's Guide via Google D...
by Jason.Jonkman
Mon Jun 22, 2020 7:55 am
Forum: Computer-Aided Engineering Software Tools
Topic: BModes and PreComp
Replies: 3
Views: 110

Re: BModes and PreComp

Dear Balazs, Regarding (1), I would guess your version of the NWTC Library is newer than what BModes is expecting. Which version of BModes are you trying to compile; is it 1.03.01? Can you compile with the old version of the NWTC Library found here: https://drive.google.com/file/d/1bMAxpls5EbGrt2j5v...
by Jason.Jonkman
Mon Jun 22, 2020 7:41 am
Forum: General
Topic: Static Pushover Analysis
Replies: 1
Views: 44

Re: Static Pushover Analysis

Dear Dhaneesh,

Not directly, but I'm sure this would be possible with a small change to the source code, e.g, by introducing a slowly increasing force applied to the tower top.

Best regards,
by Jason.Jonkman
Mon Jun 22, 2020 7:00 am
Forum: Structural Analysis
Topic: Using Aggregate Mass in ADAMS to Check NREL CS_Monopile.bmi
Replies: 7
Views: 6114

Re: Using Aggregate Mass in ADAMS to Check NREL CS_Monopile.bmi

Dear Jing.Li,

I confirm that ixx_tip is the side-to-side inertia about the x axis passing through the center of mass of the rotor-nacelle assembly.

Best regards,

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