Search found 5770 matches

by Jason.Jonkman
Thu May 06, 2021 6:41 am
Forum: Computer-Aided Engineering Software Tools
Topic: Natural frequency DeepCWind and Random Seeds
Replies: 22
Views: 530

Re: Natural frequency DeepCWind and Random Seeds

Dear Andre, You appear to be running the old MBC scripts for FAST v7. In FAST v8 and OpenFAST, you should use fx_mbc3.m , followed by campbell_diagram_data.m , as documented at the bottom of the page here: https://github.com/OpenFAST/matlab-toolbox. OpenFAST allows you to linearize a model at any po...
by Jason.Jonkman
Thu May 06, 2021 6:31 am
Forum: Inflow Turbulence
Topic: Turbulent wind for DLC 1.4 (ECD gust)
Replies: 6
Views: 405

Re: Turbulent wind for DLC 1.4 (ECD gust)

Hi Chaitanya,

I have not followed up yet, but I support the development of the IEC 61400-3-2 floating wind design standard and I'll ask that question at an upcoming meeting.

Best regards,
by Jason.Jonkman
Thu May 06, 2021 6:30 am
Forum: Testing
Topic: OpenFast Regression tests
Replies: 27
Views: 15384

Re: OpenFast Regression tests

Dear Sebastian, Right now, I'm simply suggesting that the gains may need to changed, based on the results you've shown. We've verified the BeamDyn model of the NREL 5-MW baseline wind turbine against the ElastoDyn model, using the same controller in both, but we at NREL have not performed a rigorous...
by Jason.Jonkman
Wed May 05, 2021 3:34 pm
Forum: Computer-Aided Engineering Software Tools
Topic: FAST theory manual
Replies: 364
Views: 77930

Re: FAST theory manual

Sent.
by Jason.Jonkman
Wed May 05, 2021 10:55 am
Forum: Computer-Aided Engineering Software Tools
Topic: Mlife - User Defined Distribution
Replies: 21
Views: 3099

Re: Mlife - User Defined Distribution

Dear Jian, I'm not sure why you want to simulate turbulence in FAST.Farm without wake meandering, but I agree that using the default spatial coherence parameters will result in unrealistically limited wake meandering. I'm not sure I understand your "factor of 43"; from what I can tell, you...
by Jason.Jonkman
Wed May 05, 2021 10:34 am
Forum: Computer-Aided Engineering Software Tools
Topic: VTK output to binary output
Replies: 16
Views: 1470

Re: VTK output to binary output

Dear Juan, I'm not sure I fully understand your question or what you are trying to do. I agree that the ED_TowerPtLoads forces and moments are the loads applied to ElastoDyn tower model as output from other modules. AeroDyn can apply aerodynamic loads on the tower, as can tower-based TMDs (from Serv...
by Jason.Jonkman
Wed May 05, 2021 10:14 am
Forum: Computer-Aided Engineering Software Tools
Topic: Mlife - User Defined Distribution
Replies: 21
Views: 3099

Re: Mlife - User Defined Distribution

Dear Jian, Your TurbSim inputs look reasonable to me. Presumably you've also set the reasonable spatial coherence parameters, as discussed in section 5.2.3 of the FAST.Farm User's Guide and Theory Manual: https://www.nrel.gov/docs/fy21osti/78485.pdf. I'm not really sure why the tower fatigue lifetim...
by Jason.Jonkman
Wed May 05, 2021 8:57 am
Forum: Computer-Aided Engineering Software Tools
Topic: Mlife - User Defined Distribution
Replies: 21
Views: 3099

Re: Mlife - User Defined Distribution

Dear Jian, Overall your process looks correct to me. One detail you missed was the tower thickness scaling factor of 1.3, so the tower-base thickness should actually be 0.027*1.3 = 0.0351 m, which will increase LUlt of the tower-base to 458319 kNm. What does that do to the tower design life? Best re...
by Jason.Jonkman
Wed May 05, 2021 7:58 am
Forum: Computer-Aided Engineering Software Tools
Topic: Natural frequency DeepCWind and Random Seeds
Replies: 22
Views: 530

Re: Natural frequency DeepCWind and Random Seeds

Dear Andre, Interpretation of the eigensolution has been discussed many times on this forum, including a discussion of the scripts from the MATLAB Toolbox (https://github.com/OpenFAST/matlab-toolbox)--such as MBC3 and runCampbell--that can aid in the interpretation of the MATLAB eig() function. The ...
by Jason.Jonkman
Wed May 05, 2021 7:09 am
Forum: Computer-Aided Engineering Software Tools
Topic: Extreme events
Replies: 35
Views: 14707

Re: Extreme events

Dear Abhinay, The steady extreme wind model does not involve transients. The standard says a constant yaw misalignment of +/-15deg is to be used. Load cases with the steady extreme wind model are meant be simulated via quasi-steady analysis, rather than via dynamic time-domain simulations. Best rega...
by Jason.Jonkman
Wed May 05, 2021 6:42 am
Forum: Testing
Topic: OpenFast Regression tests
Replies: 27
Views: 15384

Re: OpenFast Regression tests

Dear Sebastian, I agree that the oscillations appear to be coming from the controller. I would guess the 13-s period (0.077 Hz frequency) is coming from the PI-based blade-pitch controller. Did you change this OpenFAST model (of the NREL 5-MW baseline wind turbine with blades modeled in BeamDyn) in ...
by Jason.Jonkman
Mon May 03, 2021 9:16 am
Forum: Testing
Topic: OpenFast Regression tests
Replies: 27
Views: 15384

Re: OpenFast Regression tests

Dear Sebastian, It looks like this model has not yet reached equilibrium and you are seeing the start-up transient. The oscillations in blade pitch are commensurate with the oscillations in rotor speed. The system is not in equilibrium because the blades and tower are initialized in the undeflected ...
by Jason.Jonkman
Mon May 03, 2021 7:11 am
Forum: Controls
Topic: A question concerning Cp surface generation with OpenFAST
Replies: 22
Views: 587

Re: A question concerning Cp surface generation with OpenFAST

Dear Bartosz, I'm not sure I fully understand what you are doing. As far as I could tell, you are assessing the steady-state response at 3, 11.4, 13, and 15.5 m/s by running one long simulation with slow wind-speed ramps in between. I'm not sure what you are plotting in the Torque Regions.png images...
by Jason.Jonkman
Mon May 03, 2021 6:47 am
Forum: Computer-Aided Engineering Software Tools
Topic: Running OC4 DeepCWind for wind only
Replies: 6
Views: 156

Re: Running OC4 DeepCWind for wind only

Dear Andre, A parked or idling rotor is typically modeled with the blade leading edge facing the wind (to reduce aerodynamic loads), typically using BlPitch = 90deg (or so); pitch angles typically don't exceed this maximum value. A wind turbine operating below rated typically has blades pitched to f...
by Jason.Jonkman
Mon May 03, 2021 6:42 am
Forum: Computer-Aided Engineering Software Tools
Topic: Changing water depth for DeepCwind Model etc.
Replies: 20
Views: 553

Re: Changing water depth for DeepCwind Model etc.

Dear Andre,

Free-decay simulations of floating offshore wind turbines are typically run without incident waves. This means HydroDyn is enabled and WaveMod = 0, in which case the WaveSeed(s) are not used by HydroDyn.

Best regards,

Go to advanced search