Good morning,
I am using the standalone AeroDyn driver to perform BEM computations on the Enercon E53 turbine model. In the AeroDyn input file, I have specified the required parameters like WakeMod=1, AFAeroMod=1, AFNames, etc. In the AeroDyn Driver input file, I have given the turbine data for the E53 turbine. I would like to know, if I do not know the steady state operating points for this turbine, is there any way that the standalone AeroDyn driver can determine the operating points that limit the aerodynamic power by finding the correct pitch and rpm settings?
I currently have a set of operating points for the E53 model, which I put under Combined-Case Analysis as shown below:
When I run the AeroDyn driver, it simply finds the output values corresponding to the operating points at each wind speed, and gives me a power curve that looks like this-
As I understand, the AeroDyn driver does not know what the rated power is, and it finds the power based on the pitch, rpm and airfoil data. One way that I could get the correct operating points would be to run a complete aero-servo-elastic simulation and determine the operating points that will limit the power at rated value. At this point I am unable to do this, is there another way to do it? I will be very grateful for any help regarding this matter 
Thanks in advance,
Best regards,
Vishal Sairam
Dear Vishal,
Indeed, the power curve you are showing does not look what I would expect at high wind speeds.
One would normally look at a plot of power coefficient (RtAeroCp in AeroDyn v15) versus tip-speed ratio (RtTSR) and blade-pitch angle (BαPitch), which can be generated by running a series of AeroDyn driver simulatison. Below rated, I would expect normal operation to target the peak of this curve. Above rated, I would expect the blade pitch angle to increase and the tip-speed ratio to decrease so as to maintain a fixed (rated) rotor speed and rated power.
Best regards,
Dear Jason,
Than you for your reply. I tried including the blade-pitch angle as one of the output channels in the AeroDyn driver, but it gave an error. I used the same channel name as you had mentioned- “BαPitch”. I tried searching the OutListParameters.xlsx file to see if this output was available in AeroDyn, but I could not find it. Is there another channel name that should be given instead? I would be very grateful if you could tell me this
Best regards,
Vishal S
Dear Vishal,
You must replace “α” in the name with the blade number, e.g., B1Pitch for blade 1; likewise for blades 2 and 3.
The AeroDyn v15 outputs are documented on readthedocs: openfast.readthedocs.io/en/mast … t-channels.
Best regards,
Dear Jason,
I have a question regarding the input file for AeroDyn v15 and the airfoil data file.
If I turn off unsteady aerofoil theory in the AeroDyn v15 input file, and have the line called “InclUAdata” in the airfoil data file as “False”, then it does not matter what airfoil polars I have as input and have the same lines copied from one of the NREL model airfoil files right? I see that the 32 UA parameters are airfoil specific so if I am using an airfoil whose UA parameters I do not know, can I just turn off unsteady aerodynamics and avoid having these airfoil specific parameters in the input file?
For instance, I am using a blended airfoil series between NACA and DU airfoil series. I do not know the UA parameters for these airfoils but I have a list of aerodynamic polars. can I use the same lines as from a generic airfoil data file and just change the Cl and Cd values keeping “InclUAdata” false?
Thanks in advance.
Best regards,
Vishal
Dear Vishal,
Typically the term “airfoil polars” refers to the lift and drag (and, perhaps, pitching-moment) data as a function of angle of attack; you always need these data in the airfoil data input file. But when InclUAdata = False, the 32 UA model parameters do not need to be specified in the airfoil data file, and in that case, AFAeroMod should be set to 1.
Best regards,
Dear Jason,
is it correct if InclUAdata = False and AFAeroMod = 2, all UA model parameters are determined by the code (AeroDyn)?
Best regards,
Lukas
Dear @Lukas.Glaser,
Yes, that is correct. If InclUAdata = FALSE in the AeroDyn airfoil data input file, all unsteady airfoil parameters will rely on internal DEFAULT values.
Best regards,
Dear @Jason.Jonkman ,
Would you recommend using the internal DEFAULT values instead of using the AirfoilPrep DynStall Excel spreadsheet or AirfoilPreppy?
Cuz I find it sometimes pretty hard regarding the UA upper and lower stall values (alpha1 & alpha2) as they are very dependent on how you set the linear AoA range in airfoilpreppy. Even though the AirfoilPrep Excel sheet isn’t able to calculate these, and they depend on a guess!
Best regards,
Lukas
Dear @Lukas.Glaser,
I would say that the DEFAULT values are OK for the casual user or those without specific UA experience. The values are available to be set with specific expertise or more advanced users so as to tail UA to get better results. In addition to the old AirfoilPrep spreadsheet and AirfpoilPreppy, there are UA tools in the MATLAB Toolbox (matlab-toolbox/Utilities at main · OpenFAST/matlab-toolbox · GitHub) and python-based OpenFAST Toolbox (openfast_toolbox/openfast_toolbox/airfoils at main · OpenFAST/openfast_toolbox · GitHub).
Best regards,
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