NREL 5-MW reference turbine - CP, CQ, CT Coefficients

[Hendrik.Groeger]

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

[Jason.Jonkman]

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,

[Younes.Oudich]

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:

AERODYN_CP.zip

I hope this helps.

Kindest regards

Younes

[Hendrik.Groeger]

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

[Hendrik.Groeger]

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

[Jason.Jonkman]

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,

[Hendrik.Groeger]

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

[Jason.Jonkman]

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,

[Younes.Oudich]

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

[Hendrik.Groeger]

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

[Jason.Jonkman]

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,

[Younes.Oudich]

Dear all,

I made a MATLAB code that gives the Cp and Ct depending on pitch angle and TSR. The files can be downloaded here. The script is named “ComputeCp_Ct_code.m”. Data of Cp and Ct have already been computed and saved in “AERODYN_CP_CT.mat”. The script “ComputeCp_Ct_code.m” as it is now loads the data and plots it. There is a commented code in the script that shows how the Cp and Ct data are computed from scratch. If you want to do so from scratch, you can uncomment and change the location of the files needed. It is heavy computational and the final results are given directly in “AERODYN_CP_CT.mat”.

Here are some comments:

• The negative values have been changes to NAN values.
• For maximum Cp, the optimal TSR found is 7.55, and the optimal pitch angle is 0°, as in the reference of 5MW NREL documentation.
• To check the validity of the thrust coefficient (Ct), I compared the results with the ones obtained in the article “Flexible Multibody Dynamic Modeling of a Floating Wind Turbine”. The comparison results are given below, where the ones from the article are shown left, while the ones found in the script are shown right.
  
  

I hope this helps everyone in the future.

Kindest regards

Younes

[Jundong.Wang]

Dear @Jason.Jonkman
I am currently conducting a coupled simulation study on the feedback of large-scale offshore wind farms (OWFs) on tropical cyclones, using the WRF model with the Fitch wind farm parameterization. A key challenge I am facing involves accurately representing non-operating wind turbines (e.g., shutdown due to high wind speeds exceeding the cut-out threshold) without modifying the source code of WRF-Fitch or OpenFAST.

I would greatly appreciate your insights on the following questions:

1. Can we use OpenFAST’s RtAeroCt to approximate the residual drag of non-operating turbines?
   Under typical conditions, RtAeroCt reflects the thrust generated by aerodynamic loading on the rotor. However, in shutdown mode (e.g., wind speed at >25 m/s ), RtAeroCt drops sharply and may become very small.
   I’m concerned that this might underestimate the passive aerodynamic and structural drag still present from the tower and nacelle, which can influence the atmospheric flow.

2. Is it possible to use the TwrShadow model in AeroDyn15 to represent tower-induced drag under shutdown conditions?
   I considered enabling TwrShadow to reflect tower effects, hoping it might provide a proxy for structural drag. However, as far as I understand:

• TwrShadow modifies inflow velocities to the blades, not the background wind field;
• It does not provide a total thrust-like output;
• Therefore, it may not be suitable to approximate an effective Ct for idle turbines in WRF-Fitch.
  Can you confirm whether this reasoning is correct?

3. Structural drag-based approach for calculating effective Ct : is this valid and accepted?
   In the absence of a reliable Ct from OpenFAST for shutdown conditions, I propose to compute an effective drag-based Ct based on turbine geometry as:
   
   CD is the drag coefficient for a cylinder (~1.0–1.2),
   Aprojected​ is the frontal area of the tower and nacelle,
   Arotor=πR^2, where R is rotor radius.
   This value can be used in the wrf-wind-turbine.tbl file as the effective Ct for non-operating turbines under high wind speed conditions. This approach avoids modifying source code while approximating the physical drag exerted by the turbine structures.

Is this approach scientifically sound, and has it been validated or referenced in existing work?

Have other users faced similar questions when modeling passive (non-operational) turbines in WRF-Fitch? Are there any suggested practices or published case studies that handle this issue effectively?

Best regards,
Junius Wang

[Jason.Jonkman]

Dear @Jundong.Wang,

Here are my responses:

1. AeroDyn output RtAeroCt functions both for operational and nonoperational rotors; however, RtAeroCt only refers to the aerodynamic thrust on the rotor, which will be quite small if a rotor is parked or idling with all blades feathered, the rotor aligned with the prevailing wind. In this case, the aerodynamic loads on the nacelle and tower will be much larger than those on the rotor. AeroDyn can compute loads on the nacelle and tower, but these terms are not included in RtAeroCt; rather they are output from AeroDyn separately.

2. AeroDyn’s TwrShadow models capture, like you said, the influence of the tower on the wind field’s influence on the blades. Aerodynamic loads on the tower can be computed in AeroDyn by setting TwrAero = TRUE. Likewise, aerodynamic loads on the nacelle can be enabled by setting NacelleDrag = TRUE.

3. I’m not fully sure what WRF needs, but I would suggest combining the aerodynamic loads on the rotor, nacelle, and tower output separately from AeroDyn into a set of total loads in your own post-processing step. If you need these normalized into some effective Ct, you can compute that yourself in your post-processing step as well.

Best regards,

[Jundong.Wang]

Dear @Jason.Jonkman
Thank you very much for your reply; it has helped resolve many of my questions. However, I still have two issues I would like to consult with you about.

1. Regarding the influence of the tower structure, it seems that I can use data from at most 9 nodes for my calculations. However, the 5MW OC4 floating wind turbine should use data from 11 nodes. I’m unsure if this will have any effect; can I ignore it?
2. Secondly, I noticed that if I want to calculate the drag force of the nacelle, I should enter the relevant data in the Nacelle Properties section. However, after looking through several other 5MW models, I found that, just like in the 5MW_OC4Semi_WSt_WavesWN files, these values are all set to zero. Like this:

======  Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
0                      VolNac      - Nacelle volume (m^3)
0.0, 0.0, 0.0   NacCenB            - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
0, 0, 0      NacArea        - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
0, 0, 0   NacCd          - Drag coefficient for the nacelle areas defined above (-)
0, 0, 0         NacDragAC          - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)

While reviewing the technical manual for AeroDyn Driver, I noticed that in the Hub and nacelle inputs section, the example is given as follows:

======  Hub Properties ============================================================================== [used only when Buoyancy=True]
7.0   VolHub                - Hub volume (m^3)
0.0   HubCenBx              - Hub center of buoyancy x direction offset (m)
======  Hub Properties ============================================================================== [used only when Buoyancy=True]
5.0   VolHub                - Hub volume (m^3)
0.2   HubCenBx              - Hub center of buoyancy x direction offset (m)
======  Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
32.0            VolNac      - Nacelle volume (m^3)
0.3, 0.0, 0.05  NacCenB     - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
4.67, 20.15, 20.15 NacArea  - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
0.5, 0.5, 0.5   NacCd       - Drag coefficient for the nacelle areas defined above (-)
0.43, 0, 0      NacDragAC   - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
======  Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
32.0            VolNac      - Nacelle volume (m^3)
0.3, 0.0, 0.05  NacCenB     - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
4.67, 20.15, 20.15 NacArea  - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
0.5, 0.5, 0.5   NacCd       - Drag coefficient for the nacelle areas defined above (-)
0.43, 0, 0      NacDragAC   - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)

The following figure shows the output results. I suspect this is related to the cabin settings.

In addition, I have attached the complete AeroDyn input file.

------- AERODYN INPUT FILE --------------------------------------------------------------------------
NREL 5.0 MW offshore baseline aerodynamic input properties.
======  General Options  ============================================================================
True                  Echo        - Echo the input to "<rootname>.AD.ech"? (flag)
"default"              DTAero      - Time interval for aerodynamic calculations {or "default"} (s)
0                      Wake_Mod    - Wake/induction model (switch) {0=none, 1=BEMT, 3=OLAF} [Wake_Mod cannot be 2 or 3 when linearizing]
1                      TwrPotent   - Type tower influence on wind based on potential flow around the tower (switch) {0=none, 1=baseline potential flow, 2=potential flow with Bak correction}
1                      TwrShadow   - Calculate tower influence on wind based on downstream tower shadow (switch) {0=none, 1=Powles model, 2=Eames model}
True                   TwrAero     - Calculate tower aerodynamic loads? (flag)
False                  CavitCheck  - Perform cavitation check? (flag) [UA_Mod must be 0 when CavitCheck=true]
False                  Buoyancy    - Include buoyancy effects? (flag)
True                  NacelleDrag - Include Nacelle Drag effects? (flag)
False                  CompAA      - Flag to compute AeroAcoustics calculation [used only when Wake_Mod = 1 or 2]
"unused"               AA_InputFile - AeroAcoustics input file [used only when CompAA=true]
======  Environmental Conditions  ===================================================================
"default"              AirDens     - Air density (kg/m^3)
"default"              KinVisc     - Kinematic viscosity of working fluid (m^2/s)
"default"              SpdSound    - Speed of sound in working fluid (m/s)
"default"              Patm        - Atmospheric pressure (Pa) [used only when CavitCheck=True]
"default"              Pvap        - Vapour pressure of working fluid (Pa) [used only when CavitCheck=True]
======  Blade-Element/Momentum Theory Options  ====================================================== [unused when Wake_Mod=0 or 3, except for BEM_Mod]
1                      BEM_Mod     - BEM model {1=legacy NoSweepPitchTwist, 2=polar} (switch) [used for all Wake_Mod to determine output coordinate system]
--- Skew correction
1                      Skew_Mod    - Skew model {0=No skew model, -1=Remove non-normal component for linearization, 1=skew model active}
False                  SkewMomCorr - Turn the skew momentum correction on or off [used only when Skew_Mod=1]
default                SkewRedistr_Mod - Type of skewed-wake correction model (switch) {0=no redistribution, 1=Glauert/Pitt/Peters, default=1} [used only when Skew_Mod=1]
"default"              SkewRedistrFactor - Constant used in Pitt/Peters skewed wake model {or "default" is 15/32*pi} (-) [used only when Skew_Mod=1 and SkewRedistr_Mod=1]
--- BEM algorithm 
True                   TipLoss     - Use the Prandtl tip-loss model? (flag) [unused when Wake_Mod=0 or 3]
True                   HubLoss     - Use the Prandtl hub-loss model? (flag) [unused when Wake_Mod=0 or 3]
True                   TanInd      - Include tangential induction in BEMT calculations? (flag) [unused when Wake_Mod=0 or 3]
False                  AIDrag      - Include the drag term in the axial-induction calculation? (flag) [unused when Wake_Mod=0 or 3]
False                  TIDrag      - Include the drag term in the tangential-induction calculation? (flag) [unused when Wake_Mod=0,3 or TanInd=FALSE]
"Default"              IndToler    - Convergence tolerance for BEMT nonlinear solve residual equation {or "default"} (-) [unused when Wake_Mod=0 or 3]
100                    MaxIter     - Maximum number of iteration steps (-) [unused when Wake_Mod=0]
--- Shear correction
False                  SectAvg     - Use sector averaging (flag)
1                      SectAvgWeighting - Weighting function for sector average {1=Uniform, default=1} within a sector centered on the blade (switch) [used only when SectAvg=True]
default                SectAvgNPoints - Number of points per sectors (-) {default=5} [used only when SectAvg=True]
default                SectAvgPsiBwd - Backward azimuth relative to blade where the sector starts (<=0) {default=-60} (deg) [used only when SectAvg=True]
default                SectAvgPsiFwd - Forward azimuth relative to blade where the sector ends (>=0) {default=60} (deg) [used only when SectAvg=True]
--- Dynamic wake/inflow
0                      DBEMT_Mod   - Type of dynamic BEMT (DBEMT) model {0=No Dynamic Wake, -1=Frozen Wake for linearization, 1:constant tau1, 2=time-dependent tau1, 3=constant tau1 with continuous formulation} (-)
4                      tau1_const  - Time constant for DBEMT (s) [used only when DBEMT_Mod=1 or 3]
======  OLAF -- cOnvecting LAgrangian Filaments (Free Vortex Wake) Theory Options  ================== [used only when Wake_Mod=3]
"unused"               OLAFInputFileName - Input file for OLAF [used only when Wake_Mod=3]
======  Unsteady Airfoil Aerodynamics Options  ====================================================
True                   AoA34       - Sample the angle of attack (AoA) at the 3/4 chord or the AC point {default=True} [always used]
2                      UA_Mod      - Unsteady Aero Model Switch (switch) {0=Quasi-steady (no UA), 2=B-L Gonzalez, 3=B-L Minnema/Pierce, 4=B-L HGM 4-states, 5=B-L HGM+vortex 5 states, 6=Oye, 7=Boeing-Vertol}
True                   FLookup     - Flag to indicate whether a lookup for f' will be calculated (TRUE) or whether best-fit exponential equations will be used (FALSE); if FALSE S1-S4 must be provided in airfoil input files (flag) [used only when UA_Mod>0]
3               IntegrationMethod  - Switch to indicate which integration method UA uses (1=RK4, 2=AB4, 3=ABM4, 4=BDF2)
0                      UAStartRad  - Starting radius for dynamic stall (fraction of rotor radius [0.0,1.0]) [used only when UA_Mod>0; if line is missing UAStartRad=0]
1                      UAEndRad    - Ending radius for dynamic stall (fraction of rotor radius [0.0,1.0]) [used only when UA_Mod>0; if line is missing UAEndRad=1]
======  Airfoil Information =========================================================================
1                      AFTabMod    - Interpolation method for multiple airfoil tables {1=1D interpolation on AoA (first table only); 2=2D interpolation on AoA and Re; 3=2D interpolation on AoA and UserProp} (-)
1                      InCol_Alfa  - The column in the airfoil tables that contains the angle of attack (-)
2                      InCol_Cl    - The column in the airfoil tables that contains the lift coefficient (-)
3                      InCol_Cd    - The column in the airfoil tables that contains the drag coefficient (-)
4                      InCol_Cm    - The column in the airfoil tables that contains the pitching-moment coefficient; use zero if there is no Cm column (-)
0                      InCol_Cpmin - The column in the airfoil tables that contains the Cpmin coefficient; use zero if there is no Cpmin column (-)
8                      NumAFfiles  - Number of airfoil files used (-)
"../5MW_Baseline/Airfoils/Cylinder1.dat" AFNames - Airfoil file names (NumAFfiles lines) (quoted strings)
"../5MW_Baseline/Airfoils/Cylinder2.dat"
"../5MW_Baseline/Airfoils/DU40_A17.dat"
"../5MW_Baseline/Airfoils/DU35_A17.dat"
"../5MW_Baseline/Airfoils/DU30_A17.dat"
"../5MW_Baseline/Airfoils/DU25_A17.dat"
"../5MW_Baseline/Airfoils/DU21_A17.dat"
"../5MW_Baseline/Airfoils/NACA64_A17.dat"
======  Rotor/Blade Properties  =====================================================================
True                   UseBlCm     - Include aerodynamic pitching moment in calculations? (flag)
"../5MW_Baseline/NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(1) - Name of file containing distributed aerodynamic properties for Blade #1 (-)
"../5MW_Baseline/NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(2) - Name of file containing distributed aerodynamic properties for Blade #2 (-) [unused if NumBl < 2]
"../5MW_Baseline/NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(3) - Name of file containing distributed aerodynamic properties for Blade #3 (-) [unused if NumBl < 3]
======  Hub Properties ============================================================================== [used only when Buoyancy=True]
0                      VolHub      - Hub volume (m^3)
0                      HubCenBx    - Hub center of buoyancy x direction offset (m)
======  Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
0                      VolNac      - Nacelle volume (m^3)
0.0, 0.0, 0.0   NacCenB            - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
0, 0, 0      NacArea        - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
0, 0, 0   NacCd          - Drag coefficient for the nacelle areas defined above (-)
0, 0, 0         NacDragAC          - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
======  Tail Fin Aerodynamics =======================================================================
False                  TFinAero    - Calculate tail fin aerodynamics model (flag)
"unused"               TFinFile    - Input file for tail fin aerodynamics [used only when TFinAero=True]
======  Tower Influence and Aerodynamics ============================================================ [used only when TwrPotent/=0, TwrShadow/=0, TwrAero=True, or Buoyancy=True]
11                     NumTwrNds   - Number of tower nodes used in the analysis (-) [used only when TwrPotent/=0, TwrShadow/=0, TwrAero=True, or Buoyancy=True]
TwrElev        TwrDiam        TwrCd          TwrTI          TwrCb         ! TwrTI used only when TwrShadow=2; TwrCb used only when Buoyancy=True
(m)            (m)            (-)            (-)            (-)           
1.0000000E+01  6.5000000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
1.7760000E+01  6.2400000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
3.5520000E+01  5.9700000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
4.3280000E+01  5.7100000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
5.1040000E+01  5.4500000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
4.8800000E+01  5.1800000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
6.6560000E+01  4.9200000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
7.4320000E+01  4.6600000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
8.2080000E+01  4.4000000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
7.9840000E+01  4.1300000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
9.7600000E+01  3.8700000E+00  1.0000000E+00  1.0000000E-01  0.0000000E+00
======  Outputs  ====================================================================================
True                  SumPrint    - Generate a summary file listing input options and interpolated properties to "<rootname>.AD.sum"? (flag)
3                      NBlOuts     - Number of blade node outputs [0 - 9] (-)
1, 9, 19               BlOutNd     - Blade nodes whose values will be output (-)
9                      NTwOuts     - Number of tower node outputs [0 - 9] (-)
1, 2, 3, 4, 5, 6, 7, 8, 9                TwOutNd     - Tower nodes whose values will be output (-)
                       OutList     - The next line(s) contains a list of output parameters.  See OutListParameters.xlsx for a listing of available output channels, (-)
RtArea
RtAeroCt
RtAeroFxi
RtAeroFyi
RtAeroFzi
NcFdx
NcFdy
NcFdz
TwN1Fdx
TwN2Fdx
TwN3Fdx
TwN4Fdx
TwN5Fdx
TwN6Fdx
TwN7Fdx
TwN8Fdx
TwN9Fdx
TwN1Fdy
TwN2Fdy
TwN3Fdy
TwN4Fdy
TwN5Fdy
TwN6Fdy
TwN7Fdy
TwN8Fdy
TwN9Fdy 
END of OutList section (the word "END" must appear in the first 3 columns of the last OutList line)
---------------------- NODE OUTPUTS --------------------------------------------
1                      BldNd_BladesOut  - Number of blades to output all node information at.  Up to number of blades on turbine. (-)
ALL                    BldNd_BlOutNd   - Specify a portion of the nodes to output. {"ALL", "Tip", "Root", or a list of node numbers} (-)
                       OutList_Nodal - The next line(s) contains a list of output parameters.  See OutListParameters.xlsx for a listing of available output channels, (-)
END (the word "END" must appear in the first 3 columns of this last OutList line in the optional nodal output section)
====================================================================================================

Best Regards,
Junius

[Jason.Jonkman]

Dear @Jundong.Wang,

Regarding (1), yes, there is an unfortunate limitation of 9 tower nodal outputs available from AeroDyn. To get around this limitation, you have a few options. You could skip a couple nodes for output and interpolate in between to estimate what they are. You could run OpenFAST twice and output data from all nodes. Or you could change the source code to output more nodes or the total integrated aerodynamic loads on the tower.

Regarding (2), the details of the nacelle dimensions and drag where not in the original specification for the NREL 5-MW baseline wind turbine. The example you copied from the AeroDyn readthedocs is just an example, and not tied to the NREL 5-MW baseline turbine. I suggest making your own assumptions for your own purposes.

Best regards,

[Jundong.Wang]

@Jason.Jonkman

Thank you very much for your suggestion. I will further look for relevant information and then make reasonable assumptions.

Best regards,