NWTC

[size=100]Dear All, I am trying to obtain the hydrodynamic coefficients (added mass, radiation damping), first order wave excitation force (magnitude and the phase angle) of MIT/NREL TLP by using NEMOH panel method solver. I am attaching my results where I compared : - NEMOH solution (Blue data ser...

Dear All & Dear Jason, Description: I would like to expand the discussion to MIT NREL TLP analysis with MoorDyn. In the FAST directory, I can't see the MoorDyn code. Has anyone tried on that before? I understand that MoorDyn is based on a lumped-mass approach which is capable of modelling the mo...

Dear Jason & Dear All, 1) Is there any reference value for the damping ratio values from free decay analysis of MIT NREL TLP? I've checked Matha (2009) but I can not see. 2) I am checking the hydrodynamic solution method (potential flow or strip theory or both) of the MIT/NREL TLP from the "...

Dear Jason & Dear All, I am working on the MIT NREL TLP model, which is readily available in Model #23 of FAST. As we know that pitch response and tower bending response of the structure is coupled. I want to obtain the pure pitch frequency of the structure. To get that, I switch TwFADOF1, TwFAD...

Dear Mustafa, Yes, you can use ElastoDyn outputs TwHt*TDxt, TwHt*TDyt, and TwHt*TDzt to get the xt, yt, and zt displacements, respectively, at up to 9 output nodes along the tower, where * is between 1 and 9. Best regards, Dear Jason, Thanks a lot for your time and help... Sincerely, Mustafa Vardar...

Jason.Jonkman wrote:Dear Mustafa,

Instead of providing a unit impulse, you can set an initial tower-top displacement (in the ElastoDyn module) to conduct a free-decay test of the tower oscillation.

Best regards,

Dear Jason,

Thanks a lot for your time and help...

Sincerely,
Mustafa Vardaroglu

Dear Jason, I am trying to see the horizontal displacements along the z-axis. "TTDspFA" parameter from ElastoDyn gives the displacement of the tower top, in the fore aft direction. I am aware that it is possible to get the bending moments along the tower by specifying node numbers to "...

Dear Jason,

In addition to the platform natural frequencies, is there a way to conduct a free decay test on tower oscillations? Such as an application of unit impulse to the tower?

Sincerely,
Mustafa Vardaroglu

Dear Jason, Matha et al. (2009) " Model Development and Loads Analysis of an Offshore Wind Turbine on a Tension Leg Platform, with a Comparison to Other Floating Turbine Concepts", Table 6. gives 0.6311 Hz for the 1st Tower F-A natural frequency of the MIT NREL TLP Final design. Jonkman et...

Dear Jason, Thanks for your help. I execute the FAST code in MATLAB by simply running: command_3=('FAST_x64 Test23.fst') [status,cmdout] = system(command_3) Once the FAST terminates normally, I immediately call the ReadFASTbinary function: r=ReadFASTbinary('Test23.outb') Sorry for taking your time. ...

Dear Jason, Thanks for sharing your time. The problem is solved after switching WaveDirMod from 1 to 0. It is stated that WaveDirMod is only used when WaveMod=2,3, or 4. I didn't switch it off, continued with the default switch, while changing WaveMod from "2" to "1". And didn't ...

Dear Jason, Thanks for your help and suggestions. I have checked all the settings in the input files and the fst file (Test23). Since I'm using the default settings, everything looks ok. I've also checked the HyrdoDyn Manual regarding on regular wave analysis. Unfortunately, I'm getting a zero respo...

Dear Mustafa, Thanks for your reply. I have tried changing the tower elevation which is 10m for semi-submersible and yet the FAST is aborting. FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SrvD_CalcOutput:Running with torque and pitch control of the NREL offshore 5MW baseline wind turb...

Dear Mr. Jonkman, Thanks for your reply. I have done the corrections. Now I am getting the following error. Generating incident wave kinematics and current time history. Reading in WAMIT output with root name ".\5MW_Baseline/HydroData/SSB". Computing radiation impulse response functions a...

Dear Jason,

May I have an unofficial copy of "FAST theory manual" for a better understanding of the background.

Sincerely,

Mustafa