Turbsim v2.0.0.7 in Fast v8.16 for 5 MW wind turbine.

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Dr. Jason,
I am looking for TurbSim Input File for NREL 5MW Baseline Turbine(Test 18).
For a land-based wind turbine, you would typically set the grid size to be about 10% more than the rotor diameter in the horizontal and vertical directions.In Test18,the value of rator diameter is 126m,so you would set the grid size to be about 138.6（126+126*0.1）. Actually I found two turbsim input files.The differences are the value of RandSeed1 and NumGrid_Z, NumGrid_Y.Should I use the first one or the second one？
The first one is downloaded from your google drive.
The second file is found on the website:
[url]http://ramslandtechnology.com/Limited_Modeling/data/5MW_onshore%20_12mps_normal_turbulence/90m_12mps_twr.inp.txt[/url]

The difference has been bolded as follows
The first one:
TurbSim Input File. Valid for TurbSim v1.50; 17-May-2010; Example file that can be used with simulations for the NREL 5MW Baseline Turbine

---------Runtime Options-----------------------------------
511347 RandSeed1 - First random seed (-2147483648 to 2147483647)
RanLux RandSeed2 - Second random seed (-2147483648 to 2147483647) for intrinsic pRNG, or an alternative pRNG: “RanLux” or “RNSNLW”
False WrBHHTP - Output hub-height turbulence parameters in binary form? (Generates RootName.bin)
False WrFHHTP - Output hub-height turbulence parameters in formatted form? (Generates RootName.dat)
False WrADHH - Output hub-height time-series data in AeroDyn form? (Generates RootName.hh)
True WrADFF - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
False WrBLFF - Output full-field time-series data in BLADED/AeroDyn form? (Generates RootName.wnd)
False WrADTWR - Output tower time-series data? (Generates RootName.twr)
False WrFMTFF - Output full-field time-series data in formatted (readable) form? (Generates RootName.u, RootName.v, RootName.w)
False WrACT - Output coherent turbulence time steps in AeroDyn form? (Generates RootName.cts)
True Clockwise - Clockwise rotation looking downwind? (used only for full-field binary files - not necessary for AeroDyn)
0 ScaleIEC - Scale IEC turbulence models to exact target standard deviation? [0=no additional scaling; 1=use hub scale uniformly; 2=use individual scales]

--------Turbine/Model Specifications-----------------------
21 NumGrid_Z - Vertical grid-point matrix dimension
21 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
630.0 AnalysisTime - Length of analysis time series [seconds]
630.0 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds)
90.0 HubHt - Hub height [m] (should be > 0.5GridHeight)
155.0 GridHeight - Grid height [m]
155.0 GridWidth - Grid width [m] (should be >= 2(RotorRadius+ShaftLength))
0 VFlowAng - Vertical mean flow (uptilt) angle [degrees]
0 HFlowAng - Horizontal mean flow (skew) angle [degrees]

The second one:
TurbSim Input File. Valid for TurbSim v1.50; 17-May-2010; Example file that can be used with simulations for the NREL 5MW Baseline Turbine; note that UsableTime has been decreased in this file so that the file distributed with the FAST CertTest isn’t as large

---------Runtime Options-----------------------------------
13428 RandSeed1 - First random seed (-2147483648 to 2147483647)
RanLux RandSeed2 - Second random seed (-2147483648 to 2147483647) for intrinsic pRNG, or an alternative pRNG: “RanLux” or “RNSNLW”
False WrBHHTP - Output hub-height turbulence parameters in binary form? (Generates RootName.bin)
False WrFHHTP - Output hub-height turbulence parameters in formatted form? (Generates RootName.dat)
False WrADHH - Output hub-height time-series data in AeroDyn form? (Generates RootName.hh)
True WrADFF - Output full-field time-series data in TurbSim/AeroDyn form? (Generates RootName.bts)
False WrBLFF - Output full-field time-series data in BLADED/AeroDyn form? (Generates RootName.wnd)
True WrADTWR - Output tower time-series data? (Generates RootName.twr)
False WrFMTFF - Output full-field time-series data in formatted (readable) form? (Generates RootName.u, RootName.v, RootName.w)
False WrACT - Output coherent turbulence time steps in AeroDyn form? (Generates RootName.cts)
True Clockwise - Clockwise rotation looking downwind? (used only for full-field binary files - not necessary for AeroDyn)
0 ScaleIEC - Scale IEC turbulence models to exact target standard deviation? [0=no additional scaling; 1=use hub scale uniformly; 2=use individual scales]

--------Turbine/Model Specifications-----------------------
31 NumGrid_Z - Verti+cal grid-point matrix dimension
31 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
630.0 AnalysisTime - Length of analysis time series [seconds]
600.0 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds) [bjj: was 630]
90.0 HubHt - Hub height [m] (should be > 0.5GridHeight)
145.0 GridHeight - Grid height [m]
145.0 GridWidth - Grid width [m] (should be >= 2(RotorRadius+ShaftLength))
0 VFlowAng - Vertical mean flow (uptilt) angle [degrees]
0 HFlowAng - Horizontal mean flow (skew) angle [degrees]

2

Dear Kaiyu.Fang,

Regarding the grid in TurbSim, our typical recommendation is to set the grid spacing in Y and Z equal to maximum chordlength of the wind turbine being simulated, which is about 5 m for the NREL 5-MW baseline wind turbine (discretization is typically a balance to minimize computational expense and refine fine enough for convergence of the solution). So, the first TurbSim model is a bit coarser than recommend (155 m/(20-1) = 7.75 m) and the second model is a bit finer than recommend (145 m/(30-1) = 4.83 m). Ideally, you’d probably use something like GridHeight = GridWidth = 140 m (10% larger than the rotor diameter) and NumGrid_Y = NumGrid_Z = 29, such that 140/(29-1) = 5 m.

Regarding the random seed, ideally you should set this differently every time you run TurbSim, so, neither file is more correct.

Best regards,

3

Dear Jason,

Thank you again for your answer. It really helps a lot.

Best regards

4

Hi everyone,

I have OpenFAST v3.5.3, I try to simulate a turbulent wind as usual. It was working with previous Fast versions but this last one it give me the error of the grid size beeing too small in z direction, even though it’s not. I don’t understand the issue. Can someone help me please?
Here is the TurbSim input file, and the OpenFAST error.
TURBSIM:

--------Turbine/Model Specifications-----------------------
29        NumGrid_Z   - Vertical grid-point matrix dimension
29        NumGrid_Y   - Horizontal grid-point matrix dimension
0.008      TimeStep    - Time step [s]
60       AnalysisTime- Length of analysis time series [s] (program will add time if necessary)
"ALL"     UsableTime  - Usable length of output time series [s] (GridWidth/MeanHHWS s added if not "ALL")
90.0     HubHt       - Hub height [m] (should be > 0.5*GridHeight)
140.00     GridHeight  - Grid height [m]
140.00     GridWidth   - Grid width [m] (should be >= 2*(RotorRadius+ShaftLength))
0         VFlowAng    - Vertical mean flow (uptilt) angle [degrees]
0         HFlowAng    - Horizontal mean flow (skew) angle [degrees]

--------Meteorological Boundary Conditions-------------------
"SMOOTH"  TurbModel   - Turbulence model (see Table 4 for valid codes)
"unused"  UserFile    - Name secondary input file for user-defined spectra or time series inputs
"3"   IECstandard - Number of the IEC standard (61400-x, x=1,2,3) with optional 61400-1 ed. number
6       IECturbc    - IEC turbulence characteristic ("A", "B", "C" or TI 
"NTM"     IEC_WindType- IEC turbulence type ("NTM", "xETM", "xEWM1", or "xEWM50" for x=class 1, 2, or 3)
default   ETMc        - IEC Extreme turbulence model "c" parameter [m/s] (or "default")
"PL"      ProfileType - Wind profile type (see Table 6 for valid codes)
"unused"  ProfileFile - Name of the file that contains user-defined input profiles
84.30     RefHt       - Height of the reference wind speed [m]
9.045      URef        - Mean wind speed at the reference height [m/s] [must be 1-hr mean for API model]
450       ZJetMax     - Height of the low-level jet [m] (70-490 m or "default", only for "JET" profile)
default   PLExp       - Power law exponent (or "default")
default   Z0          - Surface roughness length [m] (or "default")

--------Non-IEC Meteorological Boundary Conditions------------
default   Latitude    - Site latitude [degrees] (or "default")
0.05      RICH_NO     - Gradient Richardson number [-]
default   UStar       - Friction or shear velocity [m/s] (or "default")
default   ZI          - Mixing layer depth [m] (or "default")
default   PC_UW       - Hub mean u'w' Reynolds stress [m^2/s^2] (or "default" or "none")
default   PC_UV       - Hub mean u'v' Reynolds stress [m^2/s^2] (or "default" or "none")
default   PC_VW       - Hub mean v'w' Reynolds stress [m^2/s^2] (or "default" or "none")

--------Spatial Coherence Parameters----------------------------
default   SCMod1      - u-component coherence model ("GENERAL","IEC","API","NONE", or "default")
default   SCMod2      - v-component coherence model ("GENERAL","IEC","NONE", or "default")
default   SCMod3      - w-component coherence model ("GENERAL","IEC","NONE", or "default")
default   InCDec1     - u-component coherence parameters [-, m^-1] ("a b" in quotes or "default")
default   InCDec2     - v-component coherence parameters [-, m^-1] ("a b" in quotes or "default")
default   InCDec3     - w-component coherence parameters [-, m^-1] ("a b" in quotes or "default")
default   CohExp      - Coherence exponent for general model [-] (or "default")

--------Coherent Turbulence Scaling Parameters-------------------
"CertTest/EventData"  CTEventPath     - Name of the path where event data files are located
"Random"  CTEventFile - Type of event files ("LES", "DNS", or "RANDOM")
True      Randomize   - Randomize the disturbance scale and locations? (true/false)
1.0       DistScl     - Disturbance scale (ratio of wave height to rotor disk).
0.5       CTLy        - Fractional location of tower center from right to L of dataset looking downwind
0.5       CTLz        - Fractional location of hub height from the bottom of the dataset
30.0      CTStartTime - Minimum start time for coherent structures in RootName.cts [s]

OpenFAST Error:

************************************************************************************************** 
OpenFAST 
 
Copyright (C) 2024 National Renewable Energy Laboratory 
Copyright (C) 2024 Envision Energy USA LTD 
 
This program is licensed under Apache License Version 2.0 and comes with ABSOLUTELY NO WARRANTY. 
See the "LICENSE" file distributed with this software for details. 
************************************************************************************************** 
 
OpenFAST-Unversioned from 6a7a543790f3cad4a65b87242a619ac5b34b4c0f 
Compile Info: 
 - Compiler: Intel(R) Fortran Compiler 2021 
 - Architecture: 64 bit 
 - Precision: single 
 - OpenMP: No 
 - Date: May 29 2024 
 - Time: 15:13:51 
Execution Info: 
 - Date: 07/03/2024 
 - Time: 12:52:58+0200 
 
OpenFAST input file heading: 
    FAST Certification Test #18: NREL 5.0 MW Baseline Wind Turbine (Onshore) 
 
Running ElastoDyn. 
Nodal outputs section of ElastoDyn input file not found or improperly formatted. 
Running AeroDyn. 
AD15 Nodal Outputs: Nodal output section of AeroDyn input file not found or improperly formatted. 
Skipping nodal outputs. 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 1) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 2, blade 1) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 3, blade 1) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 4, blade 1) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 2) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 2, blade 2) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 3, blade 2) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 4, blade 2) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 1, blade 3) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 2, blade 3) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 3, blade 3) 
Warning: Turning off Unsteady Aerodynamics because polar has constant data. (node 4, blade 3) 
Running InflowWind. 
 
   Reading a 29x29 grid (140 m wide, 20 m to 160 m above ground) with a characteristic wind speed 
   of 9.13 m/s. This full-field file was generated by TurbSim on 03-Jul-2024 at 12:51:24. 
 
   Processed 7500 time steps of 125-Hz grid-field data (period of 60 seconds). 
Running ServoDyn. 
Running ServoDyn Interface for Bladed Controllers (using Intel Visual Fortran for Windows). 
Using legacy Bladed DLL interface. 
 
FAST_InitializeAll:FAST_Init:FAST_ReadPrimaryFile:1/VTK_fps is not an integer multiple of DT. 
FAST will output VTK information at 14.545 fps, the closest rate possible. 
 
 Time: 0 of 2 seconds.
 
FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SolveOption2c_Inp2AD_SrvD:InflowWind_Ca 
lcOutput:CalculateOutput:IfW_FlowField_GetVelAcc:Grid3DField_GetCell: G3D wind array boundaries 
violated. Grid too small in Z direction (height (Z=8.5261 m) is below the grid and no tower 
points are defined). 
 
a OpenFAST encountered an error during simulation initialization. 
 Simulation error level: FATAL ERROR 
 
 Aborting OpenFAST.

Kindest regards

5

Dear @Younes.Oudich,

OpenFAST is error because it appears that you have an aerodynamic analysis node at Z = 8.5261 m, while your TurbSim grid extends from 20 to 160 m above the ground. I would guess that you have aerodynamic analysis nodes along the tower specified in AeroDyn that are below 20 m.

Best regards,

1 Like
6

Dear @Jason.Jonkman

Thank you for the fast reply, I indeed have a node at Z=8.5261 m in my AeroDyn. I changed the size of the grid to NumGrid_Z=32 and GridHeight=155 m, and it worked.
But still I can’t understand why does the grid start from 20 m? I was expecting a grid from 0 to 140 m with NumGrid_Z=29 and GridHeight=140m. My reasoning is the highest point is at 140 m, and dZ=140/(29-1)=5 m, and so the most down point will be at 140 - 5*28 = 0 m. I miss something…

Kindest regards

Younes

7

Dear @Younes.Oudich,

See Figure 5 and accompanying text from the TurbSim User’s Guide for an explanation: https://openfast.readthedocs.io/en/main/_downloads/cb14d3e2d3533d76e405d730fea19846/TurbSim_v2.00.pdf. When GridHeight = GridWidth, the grid will be centered around the HubHt.

Best regards,

1 Like
8

Dear @Jason.Jonkman ,

Thank you for the reply and explanation, it makes sense now knowing that the top of the
grid is assumed to be aligned with the top of the rotor disk.

Kindest regards

Younes