Search found 4404 matches

by Jason.Jonkman
Wed Dec 11, 2019 4:16 pm
Forum: Tidal Current
Topic: Tidal Turbine Simulation in Open Fast - Inclusion of Hydrodynamic Added Mass
Replies: 1
Views: 12

Re: Tidal Turbine Simulation in Open Fast - Inclusion of Hydrodynamic Added Mass

Dear Ben, The ability to account for added mass in FAST v8 as described in the paper you reference was developed in a branch of FAST, which was not included in the transition to OpenFAST. We hope to merge this capability into OpenFAST at some point, but this work has not started yet. Until then, I s...
by Jason.Jonkman
Wed Dec 11, 2019 8:42 am
Forum: Computer-Aided Engineering Software Tools
Topic: Customizing Jacket model in FAST.v8
Replies: 45
Views: 23525

Re: Customizing Jacket model in FAST.v8

Dear Bowen, In addition to the moment at each joint, the axial load at each joint, together with the moment arm will also contribute to the total base reaction moment. There are also corrections for applied loads at the joint. The details are explained in section 6.5.3 of the draft SubDyn User's Gui...
by Jason.Jonkman
Wed Dec 11, 2019 7:59 am
Forum: Computer-Aided Engineering Software Tools
Topic: MCrunch
Replies: 1
Views: 6

Re: MCrunch

Dear Ning.Wang,

What problem are you running into with MCrunch?

Best regards,
by Jason.Jonkman
Wed Dec 11, 2019 7:56 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 245
Views: 32418

Re: FAST theory manual

Sent.
by Jason.Jonkman
Tue Dec 10, 2019 11:22 am
Forum: Controls
Topic: Power coefficient/Aerodynamic torque
Replies: 17
Views: 622

Re: Power coefficient/Aerodynamic torque

Dear Kumara,

Without induction, energy is not preserved in this simulation, so, energy-related quantities are not accurate. I would set WakeMod = 1.

Best regards,
by Jason.Jonkman
Tue Dec 10, 2019 11:01 am
Forum: Controls
Topic: Power coefficient/Aerodynamic torque
Replies: 17
Views: 622

Re: Power coefficient/Aerodynamic torque

Dear Kumara, Are you plotting AeroDyn output RtAeroCp? With WakeMod = 0 in AeroDyn v15, the induced velocity calculation is disabled (meaning the induction is zero and the angle of attack will be determined geometrically), so, you are not using BEM and the Betz limit can be violated. The WakeMod = 0...
by Jason.Jonkman
Tue Dec 10, 2019 10:55 am
Forum: Structural Analysis
Topic: Modeling of the NREL 5-MW wind turbine blades
Replies: 1
Views: 22

Re: Modeling of the NREL 5-MW wind turbine blades

Dear Mohsen, You haven't stated what Ref. [1], [2], or [3] are. I'm assuming [1] is the NREL 5-MW baseline wind turbine specifications report: https://www.nrel.gov/docs/fy09osti/38060.pdf and I'm assuming [3] is the FAST v7 User's Guide: https://nwtc.nrel.gov/system/files/FAST.pdf. I'm not sure what...
by Jason.Jonkman
Tue Dec 10, 2019 10:40 am
Forum: Computer-Aided Engineering Software Tools
Topic: Test04 results meaning
Replies: 2
Views: 25

Re: Test04 results meaning

Dear Tiasa, While not a physically realistic situation, when GenDOF = False, the generator will spin at a fixed speed regardless of the torques applied (even if the applied torques are not balanced). The generator model will calculate the torque and power based on the fixed speed, even if there is n...
by Jason.Jonkman
Mon Dec 09, 2019 9:01 am
Forum: Computer-Aided Engineering Software Tools
Topic: Customizing Jacket model in FAST.v8
Replies: 45
Views: 23525

Re: Customizing Jacket model in FAST.v8

Dear Bowen,

Are you comparing the sum of the local joint reaction moments to the total base reaction moment, or are you also considering the local joint forces and moment arms in the calculation?

Best regards,
by Jason.Jonkman
Mon Dec 09, 2019 7:00 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 245
Views: 32418

Re: FAST theory manual

Dear Iñaki,

Actually, I just received an error saying that your e-mail address is invalid.

Best regards,
by Jason.Jonkman
Mon Dec 09, 2019 6:59 am
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 245
Views: 32418

Re: FAST theory manual

Sent.
by Jason.Jonkman
Sat Dec 07, 2019 8:05 am
Forum: Inflow Turbulence
Topic: API wind spectrum
Replies: 18
Views: 4708

Re: API wind spectrum

Dear Mhanis, The JRSE 2013 paper from Coulling et al that you referred to originally called out an NPD (API) spectrum with a power-law profile. This is not the same as a Kaimal spectrum with an API profile. I honest don't know why you keep getting the Cholesky factorization error when using the API ...
by Jason.Jonkman
Fri Dec 06, 2019 1:33 pm
Forum: Rotor Aerodynamics
Topic: Dynamic Blade-Element/Momentum Theory (DBEMT)
Replies: 2
Views: 30

Re: Dynamic Blade-Element/Momentum Theory (DBEMT)

Dear Francisco, Unfortunately, there has not been a published paper on the development of DBEMT. The project that developed DBEMT was one were the funding ran out before the project was completed to our satisfaction. But I've attached an appendix of a currently unpublished paper that summarizes the ...
by Jason.Jonkman
Fri Dec 06, 2019 12:46 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Free decay tests
Replies: 5
Views: 242

Re: Free decay tests

Dear Florence, There are a few checks within ElastoDyn to check for physical correctness of the input settings. I would recommend setting input parameters TipRad through TowerBsHt to zero in the "Turbine Configuration" section, then make a few small adjustments (by setting values slightly ...
by Jason.Jonkman
Fri Dec 06, 2019 12:38 pm
Forum: Inflow Turbulence
Topic: API wind spectrum
Replies: 18
Views: 4708

Re: API wind spectrum

Dear Hanis, As you can probably tell, I have little knowledge of the API spectrum and have not run it myself. But looking at the TurbSim documentation, it is clear that--as you said--RefHt must be set to 10 m when using the API spectrum. I haven't looked at the source code, but I assume you could en...

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