Search found 12 matches

by Jens.Geisler
Sat Jul 04, 2020 8:09 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

Hi Drew, I just plain ignored these missing DOFs. In typical turbines they shouldn't make much of a difference. The biggest influence is probably that of the tower torsion. I didn't read the topic linked by you but I assume it suggests to emulate tower torsion with a yaw stiffness which should work ...
by Jens.Geisler
Mon Jun 08, 2020 7:45 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

And another question I received by mail: Q: The mass moment of inertia I1,I2 How you choose their values ? A: All masses, moments of inertia and stiffnesses I worked with came from a Bladed model. If you don't have such reference values, you might want to make the foundation like 10 times more inert...
by Jens.Geisler
Mon Jun 08, 2020 7:40 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

Here is another question and answer: Q: but how you choose the damping ratio as 0,0005 in some doc i found that they took as 0,15 ? why all the values of diag are 1 just 2 of them are different? (mass ans stiffness) .. A: 0.5% damping is quite usual. But 0.15% (or is it 15%?) may also work. You have...
by Jens.Geisler
Mon Jun 08, 2020 6:00 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

Hi meriem, I set the matrices as follows: - all matrices are diagonal because I didn't have more detailed data, but diagonal is usually a good choice in this case. - the damping matrix must be a real physical damping coefficient "d" (never mind the capital variable name in the script) but ...
by Jens.Geisler
Fri Jan 31, 2020 3:08 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

Here is my promised report. From what I saw so far it seems to work as expected. In the main fst file I set: 2 CompSub - Compute sub-structural dynamics (switch) {0=None; 1=SubDyn; 2=External Platform and "sub_file_path" SubFile - Name of file containing sub-structural input parameters (qu...
by Jens.Geisler
Mon Jan 27, 2020 10:46 am
Forum: Rotor Aerodynamics
Topic: Unsteady Aerodynamics, Dynamic Stall and Dynamic Wake in AeroDyn 15
Replies: 2
Views: 898

Unsteady Aerodynamics, Dynamic Stall and Dynamic Wake in AeroDyn 15

Hi, when I get the warning "Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 1, Blade = 1", does that mean that only the dynamic stall feature is disabled for that blade and foil section or also the dynamic inflow/wake effect is turned off? I am asking, because I'm actu...
by Jens.Geisler
Tue Jan 21, 2020 6:19 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modeling of linear foundation for onshore turbine

Great, thanks I'll try this and report back how it works.
by Jens.Geisler
Tue Jan 21, 2020 6:16 am
Forum: Structural Analysis
Topic: Modeling of rotor imbalance with BeamDyn
Replies: 2
Views: 720

Re: Modeling of rotor imbalance with BeamDyn

Ahhh,
sorry, I didn't realize that the three individual BeamDyn files are in the main .fst file as opposed to ElastoDyn, where the induvidual blade properties are located inside the driver file.

[Edit] posted four minutes too late :-(
by Jens.Geisler
Tue Jan 21, 2020 1:58 am
Forum: Structural Analysis
Topic: Modeling of rotor imbalance with BeamDyn
Replies: 2
Views: 720

Modeling of rotor imbalance with BeamDyn

Hi everyone, is there any way I can model a rotor mass imbalance when using BeamDyn for the blade dynamics? In ElastoDyn there are three individual files for the blade properties, so I can make one blade a bit heavier. But with BeamDyn there is only one file for all three blades, so all blades must ...
by Jens.Geisler
Tue Jan 21, 2020 1:47 am
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Re: Modelling of linear foundation

Hi Jason,
thanks for the quick reply.
Indeed I am modeling an onshore turbine. I will edit the title accordingly.
Is the file format for the SubFile the same as when CompSub=1? Or is there any place I can find an example file (already looked in the matlab-toolbox and r-test repos)?

BR
by Jens.Geisler
Sun Jan 19, 2020 11:48 pm
Forum: Structural Analysis
Topic: Modeling of linear foundation for onshore turbine
Replies: 12
Views: 1296

Modeling of linear foundation for onshore turbine

Hi everybody, I am trying to convert a model from Bladed to OpenFAST as accurate as possible. In Bladed the tower base can be either coupled to the inertial frame or to a specified mass/inertia via a single linear spring per DOF with specified stiffness. I would like to reproduce the later option wi...

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