FAST v8.09

Wind & Water Computer-Aided Engineering Software Tools
1

Good morning,

I was wondering if I could have FAST v8.09? I cannot see it available to download online. I am looking to run some historic files made for this version.

Thank you in advance,
Bruce

2

Hi Bruce,

I always recommend upgrading to the newer version of the software, but I can provide you access to FAST v8.09. I’ve temporarily placed the old archive here: drive.google.com/drive/folders/ … sp=sharing. Let me know once you’ve downloaded it and I will delete it.

Best regards,

3

Hi Jason,

Understood, thank you anyway for supplying this version. I have downloaded it, so you can delete it.

Thanks again,
Bruce

4

Done; thanks.

5

Hi again Jason,

I am trying to run a simple analysis for the extreme wind loads (i.e. drag loads only) on the WindPACT 750kW turbine. I am running fast v8.09, BlPitch=90. My time step is 0.005s. I am using a .wnd file with steady Uref = 50m/s EWM. That is most of the important info I think, let me know if you need anything else.

When I have the GenDOF=True, I seem to get normal results. When I have GenDOF=False, I seem to get NaN for almost all of my results. I have attached samples of the first couple of lines of the two output files. I have tried reducing the time step to 0.0005s, as is suggested in other threads, to no avail. I am not sure why the GenDOF=False case is not returning any results.

Thanks in advance,
Bruce
WP_0.75MW_gen_dof_off.out_sample.txt (13.9 KB)
WP_0.75MW_gen_dof_on.out_sample.txt (13.9 KB)

6

Dear Bruce,

I’m not sure.

I gather based on your output files, which don’t show any blade or tower deflections, that you have the blade and tower DOFs disabled…is that correct? Other then GenDOF, which you are toggling, do you have any structural DOFs enabled?

The outputs you are plotting are shown after 10 s of simulation. The clue as to what is happening likely occurs during the first 10 s. I suggest rerunning with TStart = 0.

Best regards,

7

Hi Jason,

You are correct, I was modelling an infinitely stiff tower for simplicity, so yes all structural DOFs were turned off.
You were correct the error is occurring after the first time step. See WP_0.75MW_time_reduced_sample.csv in the attached zip.

I have toggled the tower, blade and both tower and blade DOFs and the error are not present in any of these three cases. But surely there shouldn’t be a problem calculating the wind loads on an infinitely stiff tower? Note that the Elastodyn file attached is for the final case, with all turbine structural DOFs free.

Finally, I see that in all three cases have a final TwrBsFxt around 27kN, does this mean that Aerodyn is calculating only the drag on the blades or only on the tower?

Thanks again,
Bruce
0.75MW_drag.zip (23 KB)

8

Dear Bruce,

I can’t speak to why some models are giving NaNs while others are not, but regardless, I think the main problem is that BEDDOES and SWIRL are enabled in AeroDyn v14 for this parked/idling case, which can result in numerical instabilities. BEDDOES and SWIRL were designed to work for an operational rotor and may not function well in parked/idling situations. I suggest rerunning with STEADY and NONE, respectively.

AeroDyn does support wind loading on the tower, but I don’t see that you’ve enabled that feature in your model. There is a tower aerodynamic load model in AeroDyn v14, but its functionality is quite limited. When enabling tower aerodynamics, I suggest upgrading to AeroDyn v15. And while your at that, I suggest upgrading to OpenFAST.

Best regards,

9

Hi Jason,

I have made the switch from BEDDOES to STEADY and SWIRL to NONE and the NaN issue does not seem to appear anymore. I am happy with the results I am getting now. Thank you very much for your time on this matter.

Regarding upgrading, I agree with you and am using OpenFAST/Aerodyn v15 for my other projects.

Thanks again,
Bruce