Dear @Jason.Jonkman,
Thank you very much for your fast reply.
- I am trying to compute the steady-state performance of the NREL 5-MW baseline WT but I cannot find the files in the modules/aerodyn folder and in the openfast/5MW_Baseline folder, I cannot find an AeroDyn Driver File. Can you please tell me where I can find them?
- With the dynamic wake disabled (
DBEMT_Mod = 0), I still get illogical values. For example for a rotor speed of 20 rpm and a pitch angle of 40 deg, Cp is around -43 on average. I expect Cp to be zero or nearly zero. There is probably another severe mistake I made.
The rest is clear to me now. Thank you again.
Kind regards,
Hendrik
Dear @Hendrik.Groeger,
The NREL 5-MW baseline wind turbine is not tested in the AeroDyn driver. But you should be able edit the driver file you have with the inputs compatible with the NREL 5-MW baseline wind turbine. The inputs are similar to a subset of the inputs available in ElastoDyn: r-test/glue-codes/openfast/5MW_Land_DLL_WTurb/NRELOffshrBsline5MW_Onshore_ElastoDyn.dat at main · OpenFAST/r-test · GitHub.
Best regards,
Dear Hendrik,
I think sharing the data here in the Forum is impossible. Thus, I put it in my drive so you can download it. I have put a MATLAB script how I used AeroDyn to find the Cp curve. It takes a while for the computation. So in the end, I just saved the Cp data as “AERODYN_CP.mat”, and I load it to plot it or use it. Everything is in the MATLAB script “ComputeCpCode.m”. You only have to load “AERODYN_CP.mat” and you can run the rest directly.
If you insist on finding the results from scratch using AeroDyn, I can also send you the files. But it takes time to upload them. Here is the link to the download it:
I hope this helps.
Kindest regards
Younes
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Dear @Younes.Oudich,
This helps a whole lot and everything is working.
To get the results by the simulation, I will just try to get AeroDyn running by myself.
One more question: Do you want me to give you credit if I use your data? And if so, how?
Thank you very much for your fast reply and for sharing your results.
Best regards
Hendrik
Dear @Jason.Jonkman,
Thank you very much for your reply.
I replaced
----- Turbine(1) Geometry ---------------------------------------------------------------
True BasicHAWTFormat(1) - Flag to switch between basic or generic input format {True: next 7 lines are basic inputs, False: Base/Twr/Nac/Hub/Bld geometry and motion must follow}
0,0,0 BaseOriginInit(1) - Coordinate of tower base in base coordinates (m)
3 NumBlades(1) - Number of blades (-)
3. HubRad(1) - Hub radius (m)
140.82513 HubHt(1) - Hub height (m)
-7 Overhang(1) - Overhang (m)
-6 ShftTilt(1) - Shaft tilt (deg)
-4 Precone(1) - Blade precone (deg)
3.09343 Twr2Shft(1) - Vertical distance from the tower-top to the rotor shaft (m)
from the BAR turbine with
----- Turbine(1) Geometry ---------------------------------------------------------------
True BasicHAWTFormat(1) - Flag to switch between basic or generic input format {True: next 7 lines are basic inputs, False: Base/Twr/Nac/Hub/Bld geometry and motion must follow}
0,0,0 BaseOriginInit(1) - Coordinate of tower base in base coordinates (m)
3 NumBlades(1) - Number of blades (-)
1.5 HubRad(1) - Hub radius (m)
90 HubHt(1) - Hub height (m)
-5.0191 Overhang(1) - Overhang (m)
-5 ShftTilt(1) - Shaft tilt (deg)
-2.5 Precone(1) - Blade precone (deg)
1.96256 Twr2Shft(1) - Vertical distance from the tower-top to the rotor shaft (m)
which is the corresponding data that I found in the ElastoDyn file of the NREL 5MW baseline turbine. Is this sufficient or do I need to add more of the parameters from the baseline turbine?
Of course in the driver file, I also included the corresponding AeroDyn input file together with its airfoils and blade data.
I am sorry for the inconveniences but unfortunately, I still get results for Cp which are (way) below zero for certain pitch angles and rotor speeds. Do you have any idea what could be the reason for that?
No problem if you cannot find the time to answer soon. Since I got some data provided here, it’s not that urgent anymore. Of course, your help is still appreciated.
Kind regards,
Hendrik
Dear @Hendrik.Groeger,
I agree with your updated AeroDyn driver inputs for the NREL 5-MW baseline wind turbine.
Regarding Cp, it certainly can be negative for some combinations of rotor speed (TSR) and pitch. Are you now getting the Cp results you expect at other conditions, e.g., at zero-degree pitch for a range of TSR?
Best regards,
Dear @Jason.Jonkman,
My results so far are as follows:
which is still far from what I would expect unfortunately…
Do you have any idea of what could possibly be the mistake I made?
By the way, I changed to simulation time to be 60 seconds. The rest is kept as shown in the earlier posts.
Many thanks in advance
Best regards,
Hendrik
Dear @Hendrik.Groeger,
Your plot is a bit hard to interpret due to the strong negative Cp at off-normal conditions. Can you share the results in a 2D plot at zero-degrees pitch, or in a contour plot where any Cp below zero is limited to zero (like the plot @Younes.Oudich shared in this post from Nov 17, 2021 above)?
Best regards,
Dear Hendrik,
I am happy I could help!
For your question, no need for credit. Thank you a lot, and good luck :).
Kindest regards
Younes
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Dear @Jason.Jonkman,
this is my plot with the negative Cp values set to zero:
Like that the results look like expected, don’t they?
My confusion mostly came from the fact that I thought that negative Cp values (and especially this far below zero) shouldn’t be possible and thus there must be something wrong with my simulation. I didn’t know that simply cutting them off is the standard procedure.
The maximum value of Cp is about 0.4611 (at a pitch angle of 0 deg and TSR of around 7) which does not exactly match with the actual results of the NREL 5MW baseline turbine but is good enough considering your earlier posts which sound like that it’s normal to not obtain the exact same results. Or isn’t it?
Thank you very much for answering my questions and for all the help!
Kind regards,
Hendrik
Dear @Hendrik.Groeger,
I agree your results look close to the results from others and what I would expect.
I’m not sure I would say “cutting off” the strong negative Cp at off-normal conditions is “standard procedure”, but it does make the plot easily to interpret.
I’m glad your problem is solved.
Best regards,
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