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by Jason.Jonkman
Wed Apr 17, 2019 7:45 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Inhomogen turbulent windfield
Replies: 3
Views: 542

Re: Inhomogen turbulent windfield

Dear Arnold, FAST.Farm can be compiled and run in serial or parallel mode. Parallelization has been implemented in FAST.Farm through Open Multi-Processing (OpenMP), which allows FAST.Farm to take advantage of multi-core computers by dividing computational tasks among the cores/threads within a node ...
by Jason.Jonkman
Tue Apr 16, 2019 12:25 pm
Forum: General
Topic: Question about Betz limit
Replies: 2
Views: 11

Re: Question about Betz limit

Dear Yanda, It is common practice to use the swept area of the rotor (A_t) as the reference in the Betz limit because if the rotor was absent, the flow would not slow down and would pass through that area unaffected. The area A_u is smaller than swept area because the wind slows down due to the pres...
by Jason.Jonkman
Thu Apr 11, 2019 5:14 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Better understanding of TipClrnc and non-interference validation
Replies: 2
Views: 91

Re: Better understanding of TipClrnc and non-interference validation

Dear Alvaro, Regarding your first question, ElastoDyn assumes that the blade is a line with no volume in the calculation of TipClrncα (for blade α). Please note the AeroDyn v15 tower clearance output BαNβClrnc (for blade α and node β) is calculated more accurately and also considers the local tower ...
by Jason.Jonkman
Thu Apr 11, 2019 4:00 pm
Forum: Structural Analysis
Topic: Plotting tower shapes with Modes v.2.2
Replies: 2
Views: 80

Re: Plotting tower shapes with Modes v.2.2

Dear Natalia, In your polynomial equation, x must be between 0 (at the tower base) and 1 (at the tower top). Thus, the value of polynomial at the top (x=1) should be 1. Is this what you've done? As suggested many times on this forum, I suggest using BModes in combination with the ModeShapePolyFittin...
by Jason.Jonkman
Thu Apr 11, 2019 3:54 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Drive-train model validation (Compared to FAST)
Replies: 9
Views: 205

Re: Drive-train model validation (Compared to FAST)

Dear Thomas, As discussed in the forum posts you've linked to (and others), by nature of their calculation within the aero-elastic solution, I would only use RtAeroCp in a time-averaged sense to avoid apparent violations in the Betz limit that may occur instantaneously as a result of the calculation...
by Jason.Jonkman
Mon Apr 08, 2019 8:12 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Drive-train model validation (Compared to FAST)
Replies: 9
Views: 205

Re: Drive-train model validation (Compared to FAST)

Dear Thomas, Regarding YawPos and YawBrMzp, the torque transmitted through the yaw bearing (YawBrMzp) equals the yaw-spring stiffness times nacelle-yaw angle (YawPos) plus the yaw damping times the nacelle-yaw rate. For small yaw rates and/or yaw damping, I would expect YawPos to track YawBrMzp quit...
by Jason.Jonkman
Mon Apr 08, 2019 6:29 am
Forum: Computer-Aided Engineering Software Tools
Topic: Aerodynamic Derivatives
Replies: 3
Views: 272

Re: Aerodynamic Derivatives

Dear Adrian,

There have been some important improvements and bug fixes in AeroDyn between FAST v8.16 and OpenFAST v1 and v2. I suggest upgrading to OpenFAST.

Best regards,
by Jason.Jonkman
Fri Apr 05, 2019 6:58 am
Forum: Computer-Aided Engineering Software Tools
Topic: Drive-train model validation (Compared to FAST)
Replies: 9
Views: 205

Re: Drive-train model validation (Compared to FAST)

Dear Thomas,

Yes, I agree. I don't know exactly what conditions you simulated, but the yaw spring is quite stiff, so, I would expect small deviations in nacelle-yaw angle even under large yaw moments.

Best regards,
by Jason.Jonkman
Thu Apr 04, 2019 12:15 pm
Forum: Computer-Aided Engineering Software Tools
Topic: AeroDyn: RElm produces ill-conditioned DR
Replies: 2
Views: 112

Re: AeroDyn: RElm produces ill-conditioned DR

Dear Timo, If I recall correctly for these old versions of FAST and AeroDyn, the FAST documentation used RNodes and DRNodes and the AeroDyn documentation used RElm and. Regardless, they are equivalent. If you hub radius is really set to 1.565 m, I don't see any problem with your RElm or DR data for ...
by Jason.Jonkman
Thu Apr 04, 2019 8:45 am
Forum: General
Topic: Lay length of Mooring line
Replies: 6
Views: 185

Re: Lay length of Mooring line

Dear Krishnaveni,

I'm sorry, but I don't really understand your question. As Matt pointed out, the lay length will converge with an increasing level of discretization.

Best regards,
by Jason.Jonkman
Wed Apr 03, 2019 5:08 pm
Forum: General
Topic: Lay length of Mooring line
Replies: 6
Views: 185

Re: Lay length of Mooring line

Dear Krishnaveni,

Yes, that makes sense to me. Perhaps Matt Hall--the developer of MoorDyn--will comment further.

Best regards,
by Jason.Jonkman
Wed Apr 03, 2019 1:36 pm
Forum: General
Topic: Lay length of Mooring line
Replies: 6
Views: 185

Re: Lay length of Mooring line

Hi Krishnaveni,

Which mooring module are you using?

Best regards,
by Jason.Jonkman
Wed Apr 03, 2019 9:22 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 196
Views: 21507

Re: FAST theory manual

Sent.
by Jason.Jonkman
Wed Apr 03, 2019 7:51 am
Forum: Computer-Aided Engineering Software Tools
Topic: Adapt a FAST V7 input file to use it with OPENFAST
Replies: 2
Views: 105

Re: Adapt a FAST V7 input file to use it with OPENFAST

Dear Tomás, The FAST / OpenFAST V27 models are still being updated for use in the IEA Wind Task 31 WakeBench collaborative verification and validation project that makes use of the data from the SWiFT experiments. You can find this V27 model compatible with OpenFAST here: https://github.com/NREL/wak...
by Jason.Jonkman
Wed Apr 03, 2019 7:36 am
Forum: Computer-Aided Engineering Software Tools
Topic: Drive-train model validation (Compared to FAST)
Replies: 9
Views: 205

Re: Drive-train model validation (Compared to FAST)

Dear Thomas, Without modification of the source code, the ServoDyn module does not include built-in actuators for the generator torque and blade-pitch controllers. So, the commanded generator torque and blade-pitch angles instantaneously become the actual generator torque and blade-pitch angles. Bes...

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