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by Jason.Jonkman
Fri Apr 16, 2021 12:13 pm
Forum: Inflow Turbulence
Topic: Wind speed timeseries in .wnd file, what is the influence on the sim results?
Replies: 1
Views: 10

Re: Wind speed timeseries in .wnd file, what is the influence on the sim results?

Dear Bartosz, By a *.wnd file, presumably you are referring to the InflowWind module's uniform wind file type (WindType = 2). These files are time varying, but spatially uniform (they may include shear). Such files are typically used for deterministic IEC wind cases like gusts and direction changes....
by Jason.Jonkman
Fri Apr 16, 2021 7:00 am
Forum: General
Topic: FAST.Farm
Replies: 184
Views: 21783

Re: FAST.Farm

Dear Jiaping, Yes, the FAST.Farm User's Guide and Theory Manuel has now been finalized and published. Here: https://www.nrel.gov/docs/fy21osti/78485.pdf. Dear Hamid, The FAST.Farm source code now fully supports the functional super controller. And the super controller interface is documented in the ...
by Jason.Jonkman
Fri Apr 16, 2021 6:41 am
Forum: Computer-Aided Engineering Software Tools
Topic: Wind speed provided to controller in LES with actuator lines
Replies: 3
Views: 25

Re: Wind speed provided to controller in LES with actuator lines

Dear Ricardo, I would say the answer depends on what you are trying to model in reality. Are you trying to mimic what a nacelle-mounted anemometer would measure (in the near wake of the rotor and boundary layer of the nacelle)? Then placing the wind measurement as you have sounds correct. (Usually y...
by Jason.Jonkman
Fri Apr 16, 2021 6:36 am
Forum: Structural Analysis
Topic: Fixed offshore wind turbines Properties Question
Replies: 7
Views: 145

Re: Fixed offshore wind turbines Properties Question

Dear Tianhui, The geometry of the OC3-monopile is quite simple; and the joints and members are defined in the SubDyn input file (4 joints, 3 members, extending from -20.0001 m to 10 m above SWL). The output members and nodes are defined in the MEMBER OUTPUT LIST in the SubDyn input file. In the OC3 ...
by Jason.Jonkman
Thu Apr 15, 2021 8:32 am
Forum: Structural Analysis
Topic: Fixed offshore wind turbines Properties Question
Replies: 7
Views: 145

Re: Fixed offshore wind turbines Properties Question

Dear Tianhui, I'm not sure I understand your question. Are you asking what output member α (Mα) and output node β (Nβ) mean in SubDyn? These are described in the SubDyn documentation. Regardless, most offshore wind turbines in OpenFAST are modeled with the tower in ElastoDyn and the substructure in ...
by Jason.Jonkman
Thu Apr 15, 2021 8:24 am
Forum: Computer-Aided Engineering Software Tools
Topic: Changing water depth for DeepCwind Model etc.
Replies: 13
Views: 198

Re: Changing water depth for DeepCwind Model etc.

Dear Andre, The MassDen in MoorDyn is the mass (not weight) per unit length of the mooring line. This mass density should be expressed independent from external buoyancy. The line weight in water will be calculated by subtracting the line buoyancy from the mass times gravity. I hope that helps. Best...
by Jason.Jonkman
Wed Apr 14, 2021 2:57 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Changing water depth for DeepCwind Model etc.
Replies: 13
Views: 198

Re: Changing water depth for DeepCwind Model etc.

Dear Andre, These large skew angle and low TSR errors imply to me that the motion of the rotor is large enough that it meets or exceeds the wind velocity, which sounds extreme, but would mean the flow through the rotor can drop to near zero and the skew angle can be large. Can you confirm that the t...
by Jason.Jonkman
Wed Apr 14, 2021 2:24 pm
Forum: General
Topic: FAST.Farm
Replies: 184
Views: 21783

Re: FAST.Farm

Dear Younes, Nice video :-). From the plots, it looks like the turbine and/or controller of T2 are not reacting as expected when the wake from T1 hits T2. The error you are receiving seems to be triggered by the large (and negative) generator speed. I gather you are using the OpenFAST model of NREL ...
by Jason.Jonkman
Wed Apr 14, 2021 2:05 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Confusion about IceDyn
Replies: 10
Views: 200

Re: Confusion about IceDyn

Dear Tianhui,

I'm afraid I can't answer your question regarding the impact of ice velocity on the ice load output from IceDyn. This would be a better question for the developers (Prof. Dale Karr et al) at the University of Michigan, who I don't believe follow this forum.

Best regards,
by Jason.Jonkman
Wed Apr 14, 2021 6:44 am
Forum: Controls
Topic: ROSCO-MATLAB Implementation
Replies: 9
Views: 158

Re: ROSCO-MATLAB Implementation

Dear Bartosz, I would expect the Cp surface to be independent of wind speed when the rotor is rigid. For a flexible rotor, different wind speeds can result in different Cp surfaces, depending on how flexible the blades are. If the results are not too different, then using the Cp surface for the rigi...
by Jason.Jonkman
Wed Apr 14, 2021 6:39 am
Forum: General
Topic: FAST.Farm
Replies: 184
Views: 21783

Re: FAST.Farm

Dear Younes, FAST.Farm will throw this error when the rotor thrust is so high that the near-wake correction model is no longer valid. I expect that the downstream turbine (T2) is not operating as expected if the thrust is this high. Is 268 s, when the error is triggered, the time when the wake from ...
by Jason.Jonkman
Wed Apr 14, 2021 6:31 am
Forum: Computer-Aided Engineering Software Tools
Topic: Confusion about IceDyn
Replies: 10
Views: 200

Re: Confusion about IceDyn

Dear Tianhui, The effect of the ice loading on the tower-top acceleration and displacement will depend on the rigidity of the monopile. (If the monopile were rigid, there would be no effect of monopile loading at the tower top). It looks like the ice load has a very minor effect on the tower-top acc...
by Jason.Jonkman
Wed Apr 14, 2021 6:21 am
Forum: Controls
Topic: A question concerning Cp surface generation with OpenFAST
Replies: 5
Views: 43

Re: A question concerning Cp surface generation with OpenFAST

Dear Bartosz,

A similar question regarding GenDOF in ElastoDyn was asked and answered here: viewtopic.php?f=30&t=1110&p=4798.

Best regards,
by Jason.Jonkman
Tue Apr 13, 2021 5:03 pm
Forum: Controls
Topic: Information on couplings needed
Replies: 4
Views: 30

Re: Information on couplings needed

Dear Bartosz,

I'm not seeing anything out of the ordinary with these results.

Best regards,
by Jason.Jonkman
Tue Apr 13, 2021 6:52 am
Forum: Controls
Topic: Information on couplings needed
Replies: 4
Views: 30

Re: Information on couplings needed

Dear Bartosz, The aerodynamic loads on the rotor will include a torque, which will tend to induce roll/sway of the floater. There will also be gyroscopic loads from the spinning rotor, which mainly induce yaw, but when the rotor is tilted (due to shaft tilt or floater heal), could also induce roll. ...

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