Hi,
I’m trying to simulate the land based and monopile versions of 5MW turbine in FAST V8.12, in MATLAB Windows 32bit platform. I see a strange behaviour while running the open loop model with the test 19.fst. I see a ‘notch’ in the pitch angle, it dips to zero at about 20 seconds and rises back. Can someone explain why this happens?
Regards,
Surya.
I think this one answers the question.
“Loads Analysis of a Floating Offshore Wind Turbine Using Fully Coupled Simulation” by J.M. Jonkman and M.L. Buhl, Jr.
citeseerx.ist.psu.edu/viewdoc/do … 1&type=pdf
Hello,
I used FAST V8.10 and I ran some simulation and I verified results with the ones in this report “Verification of the New FAST v8 Capabilities for the Modelling of Fixed-Bottom Offshore Wind Turbines”.
Now I started to use V.812, I tried to produce those results again, however there are some discrepancies in the results especially for these two (Out-of-plane blade-tip deflection and Blade-root flap-wise bending moment). I uploaded my results from FAST V8.12 and those in the report. Right graphs are generated by FAST v8.12 and left ones are from the report.
I have read readme pdf file. It seems blade analysis method is improved in version 8.12. So is this discrepancy because version 8.12 analyses blades based on GEBT?
Thank you very much.
Best Regards,
Arash Hemmati,
Dear Arash,
The new structural-dynamics module, BeamDyn, introduced in FAST v8.12 will only effect the solution if it has been enabled by setting CompElast to 2 in the FAST primary input file.
From my quick comparison of your results, it looks like you’ve disabled the upwind tower-influence model of AeroDyn in FAST v8.12. By default, Test19 in the FAST CertTest uses AeroDyn v14; in AeroDyn v14, upwind tower-influence via potential flow is enabled by setting TwrShad to “NEWTOWER” and TwrPotent to True, which is also default in Test19.
Best regards,
Dear Jason,
Thank you for your reply.
I checked Aerodyn input file. They are OK. I have not disabled them.
TwrShad is “NEWTOWER”
and TwrPotent is True.
and I have not changed anything else. What do you think might be?
Thank you,
Arash Hemmati,
Dear Arash,
I just reran Test19 now (but using a steady 8 m/s wind instead of turbulence) and was able to reproduce the results from the paper–the tower influence is clearly visible in the results.
Are you sure you are running AeroDyn v14 – is CompAero set to 1 in the FAST primary input file?
Best regards,
Thank you Jason,
Now I changed InflowFile in fst file to the file that is for steady fluid (NRELOffshrBsline5MW_InflowWind_Steady8mps.dat) and the results are OK.
But before that I used this file (NRELOffshrBsline5MW_InflowWind_12mps.dat) and I changed Wind type to steady in this section and put wind speed to 8 m/s. I thought I can simulate steady wind with this file as it has option of changing wind type. It should give the same result as it can produce steady wind.
Thank you again,
Best Regards,
Arash Hemmati,
Dear Arash,
I agree that whether you use NRELOffshrBsline5MW_InflowWind_Steady8mps.dat or change NRELOffshrBsline5MW_InflowWind_12mps.dat to use steady 8 m/s wind, the results should be the same.
Best regards,
Did you also make sure there is no shear? NRELOffshrBsline5MW_InflowWind_Steady8mps.dat has PLexp = 0, but in NRELOffshrBsline5MW_InflowWind_12mps.dat, PLexp = 0.2.
You are right. It was because of PLexp. Now it is OK.
Thank you,
Arash,
