4.4.7. Using the Aeroacoustics Model in AeroDyn

A live version of this documentation is available at https://openfast.readthedocs.io/. To run the aeroacoustics model, the flag CompAA needs to be set to True at line 13 of the AeroDyn15 main input file in the inputs block General Options. When the flag is set to True, the following line must include the name of the file containing the inputs to the aeroacoustics model, which is discussed in Section 4.4.7.2.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
------- AERODYN v15.03.\* INPUT FILE ------------------------------------------------
IEA Wind Task 37 land-based reference wind turbine
====== General Options ===================================================
False          Echo        - Echo the input to "<rootname>.AD.ech"? (flag)
"default"      DT_AA       - Time interval for aerodynamic calculations {or "default"} (s)
1              WakeMod     - Type of wake/induction model (switch) {0=none, 1=BEMT}
2              AFAeroMod   - Type of blade airfoil aerodynamics model (switch
0              TwrPotent   - Type tower influence on wind around the tower (switch)
False          TwrShadow   - Calculate tower influence on wind (flag)
False          TwrAero     - Calculate tower aerodynamic loads? (flag)
False          FrozenWake  - Assume frozen wake during linearization? (flag
False          CavitCheck  - Perform cavitation check? (flag)
True           CompAA      - Flag to compute AeroAcoustics calculation
"AeroAcousticsInput.dat"   AA_InputFile
====== Environmental Conditions ==========================================
1.225.         AirDens     - Air density (kg/m^3)

File continues...

4.4.7.1. Main Input File

The aeroacoustics main input file comprises a series of inputs and flags that should be set appropriately depending on the analysis that should be run. These are split into the subfields General Options, Aeroacoustics Models, Observer Input, and Outputs.

Starting from the General Options, these are:

  • Echo – True/False: option to rewrite the input file with the correct template

  • DT_AA – Float: time step of the aeroacoustics computations. Only multiples of the time step DTAero of AeroDyn can be used. If set to default, the time step DTAero is adopted.

  • AAStart – Float: time after which the AeroAcoustics module is run.

  • BldPrcnt – Float: percentage value of blade span measured from blade tip that contributes to the noise emissions; 100% corresponds to the entire blade from tip to root.

The field Aeroacoustics Models lists all the flags for the actual noise models:

  • TIMod – Integer 0/1/2: flag to set the turbulent inflow noise model; 0 turns it off, 1 corresponds to the Amiet model discussed in Section 4.4.4.1.1, and 2 corresponds to the Simplified Guidati model presented in Section 4.4.4.1.2.

  • TICalcMeth – Integer 1/2: flag to set the calculation method for the incident turbulence intensity. When set to 1, incident turbulence intensity is defined in a user-defined grid; see Section 4.4.7.4. When set to 2, incident turbulence intensity is estimated from the time history of the incident flow.

  • TICalcTabFile – String: name of the text file with the user-defined turbulence intensity grid; see Section 4.4.7.4.

  • SurfRoughness – Float: value of \(z_{0}\) used to estimate \(L_{t}\) in the Amiet model.

  • TBLTEMod – Integer 0/1/2: flag to set the TBL-TE noise model; 0 turns off the model, 1 uses the Brooks-Pope-Marcolini (BPM) airfoil noise model (see Section 4.4.4.2.1), and 2 uses the TNO model described in Section 4.4.4.2.2.

  • BLMod – Integer 1/2: flag to set the calculation method for the boundary layer characteristics; 1 uses the simplified equations from the BPM model, 2 loads the files as described in Section 4.4.7.2. Only used if TBLTEMod is different than zero.

  • TripMod – Integer 0/1/2: if BLMod is set to 1, different semiempirical parameters are used for a nontripped boundary layer (TRipMod=0), heavily tripped boundary layer (TRipMod=1), or lightly tripped boundary layer (TRipMod=2); 2 is typically used for operational wind turbines, whereas 1 is often used for wind tunnel airfoil models.

  • LamMod – Integer 0/1: flag to activate the laminar boundary layer – vortex shedding model, presented in Section 4.4.4.3.

  • TipMod – Integer 0/1: flag to activate the tip vortex model, presented in Section 4.4.4.4.

  • RoundedTip – True/False: if TipMod=1, this flag switches between a round tip (True) and a square tip (False), see Section 4.4.4.4.

  • Alprat – Float: value of the slope of the lift coefficient curve at blade tip; see Section 4.4.4.4.

  • BluntMod – Integer 0/1: flag to activate (BluntMod=1) the trailing-edge bluntness – vortex shedding model, see Section 4.4.4.5. If the flag is set to 1, the trailing-edge geometry must be specified in the file(s) listed in the field Blade Properties.

Next, the field Blade Properties lists three file names, often but not necessarily identical, which contain the distributed properties describing the detailed geometry of the trailing edge. These are described in Section 4.4.7.5.

The field Observer Locations contains the path to the file where the number of observers (NrObsLoc) and the respective locations are specified; see Section 4.4.7.3.

Finally, the set Outputs contains a few options for the output data:

  • AWeighting – True/False: flag to set whether the sound pressure levels are reported with (True) or without (False) the A-weighting correction; see Section 4.4.5.3.

  • NAAOutFile – Integer 1/2/3: flag to set the desired output file. When set to 1, a value of overall sound pressure level at every DT_AA time step per observer is printed to file. When set to 2, the first output is accompanied by a second file where the total sound pressure level spectrum is printed per time step per observer. When set to 3, the two first outputs are accompanied by a third file where the sound pressure level spectrum per noise mechanism is printed per time step per observer. When set to 4, a fourth file is generated with the values of overall sound pressure levels per node, per blade, per observer, and per time step.

  • The following line contains the file name used to store the outputs. The file name is attached with a 1, 2, 3, and 4 flag based on the NAAOutFile options.

The file must be closed by an END command.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
------- AeroAcoustics Module v1.00.* INPUT FILE ------------------------------------------------
IEA task 37 RWT turbine -- https://github.com/IEAWindTask37/IEA-3.4-130-RWT
======  General Options  ============================================================================
False        Echo         - Echo the input to "<rootname>.AD.ech"?  (flag)
0.1          DT_AA        - Time interval for aeroacoustics calculations (s), must be a multiple of DT_Aero from AeroDyn15  (or "default")
0            AAStart      - Time after which the AeroAcoustics module is run (s)
70           BldPrcnt     - Percentage of the blade span, starting from the tip, that will contribute to the overall noise levels. (float)
======  Aeroacoustic Models  ============================================================================
2            TIMod        - Turbulent Inflow noise model  {0: none, 1: Amiet 2: Amiet + Simplified Guidati} (switch) 
1            TICalcMeth   - Method to estimate turbulence intensity incident to the profile {1: given table, 2: computed on the fly} (switch) [Only used if TIMod!=0]
"TIGrid_InVerify.txt"   TICalcTabFile - Name of the file containing the table for incident turbulence intensity (-) [Only used if TiCalcMeth == 1]
0.5          SurfRoughness- Surface roughness value used to estimate the turbulent length scale in Amiet model (m)
1            TBLTEMod     - Turbulent Boundary Layer-Trailing Edge noise calculation {0: none, 1:BPM, 2: TNO} (switch)
1            BLMod        - Calculation method for boundary layer properties,  {1: BPM, 2: Pretabulated} (switch)
1            TripMod      - Boundary layer trip model {0:no trip, 1: heavy trip, 2: light trip} (switch) [Only used if BLMod=1]
0            LamMod       - Laminar boundary layer noise model {0:none, 1: BPM}  (switch)
0            TipMod       - Tip vortex noise model {0:none, 1: BPM}  (switch)
True         RoundedTip   - Logical indicating rounded tip (flag) [Only used if TipMod=1]
1.0          Alprat       - Tip lift curve slope (Default = 1.0) [Only used if TipMod=1]
0            BluntMod     - Trailing-edge-bluntness – Vortex-shedding model {0:none, 1: BPM}  (switch)
"AABlade1.dat"    AABlFile(1)   - Name of file containing distributed aerodynamic properties for Blade #1 (-)
"AABlade1.dat"    AABlFile(2)   - Name of file containing distributed aerodynamic properties for Blade #2 (-)
"AABlade1.dat"    AABlFile(3)   - Name of file containing distributed aerodynamic properties for Blade #3 (-)
======  Observer Input  ===================================================================
"AA_ObserverLocations.dat"    ObserverLocations        - Name of file containing all observer locations X Y Z (-)
======  Outputs  ====================================================================================
False              AWeighting  - A-weighting Flag (flag)  
3                 NrOutFile  - Number of Output files. 1 for Time Dependent Overall SPL, 2 for both 1 and Frequency and Time Dependent SPL as well, or 3 for both 1 and 2 and Acoustics mechanism dependent, 4 for 1-3 and the overall sound pressure levels per blade per node per observer 
"IEA_LB_RWT-AeroAcoustics_"    AAOutFile   - No Extension needed the resulting file will have .out Name of file containing
END of input file (the word "END" must appear in the first 3 columns of this last OutList line)
---------------------------------------------------------------------------------------

4.4.7.2. Boundary Layer Inputs

When the flag BLMod is set equal to 2, pretabulated properties of the boundary layer must be provided and are used by the turbulent boundary layer – trailing-edge noise models. The file name is to be specified in the field BL_file among the inputs of the file with the airfoil polar coefficients. One airfoil file must be specified per aerodynamic station.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
! ------------ AirfoilInfo v1.01.x Input File ----------------------------------
! AeroElasticSE FAST driver
!
!
! ------------------------------------------------------------------------------
DEFAULT                  InterpOrd   ! Interpolation order to use for quasi-steady table lookup {1=linear; 3=cubic spline; "default"} [default=3]
1                        NonDimArea  ! The non-dimensional area of the airfoil (area/chord^2) (set to 1.0 if unsure or unneeded)
@"AF20_Coords.txt"       NumCoords   ! The number of coordinates in the airfoil shape file. Set to zero if coordinates not included.
AF20_BL.txt              BL_file     ! The file name including the boundary layer characteristics of the profile. Ignored if the aeroacoustic module is not called.
1                        NumTabs     ! Number of airfoil tables in this file.  Each table must have lines for Re and Ctrl.
! ------------------------------------------------------------------------------
! data for table 1

The file, in this example named AF20_BL.txt, contains 8 inputs, which are tabulated for a given number of Reynolds numbers, ReListBL, and a given number of angles of attack, aoaListBL. The inputs, which are defined nondimensionally and must be provided for the suction and pressure side of the airfoil above and below the trailing edge, are:

  • Ue_Vinf – flow velocity at the top of the boundary layer

  • Dstar\(\delta^{*}\), boundary layer displacement thickness

  • Delta\(\delta\), nominal boundary layer thickness

  • Cf – friction coefficient.

In the following example, the file was generated thanks to a Python script 4 that runs the boundary layer solver, XFoil. Notably, XFoil, by default, does not return \(\delta\), but the boundary layer momentum thickness, \(\theta\). \(\delta\) can be reconstructed using the expression from [aa-DG87]:

(4.56)\[\delta = \theta \bullet \left( 3.15 + \frac{1.72}{H - 1} \right) + \delta^{*}\]

where \(H\) is the kinematic shape factor, which is also among the standard outputs of XFoil. Because it is usually impossible to obtain these values for the whole ranges of Reynolds numbers and angles of attack, the code is set to adopt the last available values and print to screen a warning.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
! Boundary layer characteristics at the trailing edge for the airfoil coordinates of /Users/pbortolo/work/2_openfast/noise/verifyAA/OpenFAST_IEA_LB_RWT/Airfoils/AF20_Coords.txt
! Legend: aoa - angle of attack (deg), Re - Reynolds number (-, millions), PS - pressure side, SS - suction side,  Ue_Vinf - edge velocity (-), Dstar - displacement thickness (-), Delta - nominal boundary layer thickness (-) Cf  - friction coefficient (-)
4           ReListBL   -  Number of Reynolds numbers (it corresponds to the number of tables)
30          aoaListBL  -  Number of angles of attack (it corresponds to the number of rows in each table)
0.50        -  Re
aoa             Ue_Vinf_SS          Ue_Vinf_PS         Dstar_SS           Dstar_PS           Delta_SS           Delta_PS           Cf_SS              Cf_PS
(deg)           (-)                 (-)                (-)                (-)                (-)                (-)                (-)                (-)
-5.00000        8.39390e-01        -8.37360e-01        7.43700e-03        1.07730e-02        2.75094e-02        5.15849e-02        1.13200e-03        1.58200e-03 
-3.96552        8.42050e-01        -8.40230e-01        8.26600e-03        9.29500e-03        2.98650e-02        4.87153e-02        1.04400e-03        1.85700e-03 
-2.93103        8.45320e-01        -8.43690e-01        9.08800e-03        8.10000e-03        3.19790e-02        4.70045e-02        9.58000e-04        2.16500e-03 
-1.89655        8.48230e-01        -8.46710e-01        9.97400e-03        7.33700e-03        3.44024e-02        4.50456e-02        8.90000e-04        2.35800e-03 
-0.86207        8.51550e-01        -8.50140e-01        1.09130e-02        6.54100e-03        3.68822e-02        4.30884e-02        8.26000e-04        2.59900e-03 
 0.17241        8.55000e-01        -8.53670e-01        1.18900e-02        5.92900e-03        3.96199e-02        4.27416e-02        7.79000e-04        2.87100e-03 
 1.20690        8.63820e-01        -1.04207e+00        1.22130e-02        9.89500e-03        4.18890e-02        1.68156e-02        8.18000e-04       -1.77000e-04 
 2.24138        8.61500e-01        -8.60210e-01        1.40420e-02        4.88700e-03        4.51813e-02        3.93105e-02        6.78000e-04        3.28700e-03 
 3.27586        8.64430e-01        -8.63080e-01        1.52900e-02        4.57300e-03        4.85938e-02        3.82233e-02        6.39000e-04        3.44000e-03 
 4.31034        8.67960e-01        -8.66600e-01        1.65660e-02        4.09100e-03        5.17768e-02        3.63749e-02        5.96000e-04        3.69000e-03 
 5.34483        8.72300e-01        -8.70850e-01        1.81000e-02        3.81700e-03        5.43379e-02        3.52278e-02        5.09000e-04        3.86300e-03 
 6.37931        8.77930e-01        -8.76410e-01        1.98500e-02        3.39700e-03        5.69109e-02        3.31481e-02        4.18000e-04        4.13900e-03 
 7.41379        8.86840e-01        -8.85140e-01        2.22250e-02        3.15000e-03        5.81316e-02        3.19040e-02        2.64000e-04        4.36900e-03 
 8.44828        9.00620e-01        -8.98660e-01        2.54290e-02        2.75900e-03        5.91946e-02        2.95298e-02        1.01000e-04        4.76300e-03 
 9.48276        9.20300e-01        -9.17700e-01        2.99830e-02        2.48300e-03        6.07767e-02        2.75551e-02        5.00000e-06        5.16000e-03 
10.51724        9.48080e-01        -9.44440e-01        3.80160e-02        2.13200e-03        6.65531e-02        2.48447e-02       -1.60000e-05        5.76800e-03 
11.55172        9.89560e-01        -9.84930e-01        5.83630e-02        1.85700e-03        8.76076e-02        2.18890e-02       -1.50000e-05        6.49000e-03 
12.58621        1.02883e+00        -1.02353e+00        8.80990e-02        1.66700e-03        1.21588e-01        2.00072e-02       -1.30000e-05        7.20200e-03 
13.62069        1.05789e+00        -1.05226e+00        1.18914e-01        1.51000e-03        1.57264e-01        1.78004e-02       -1.10000e-05        7.74800e-03 
14.65517        1.07975e+00        -1.07394e+00        1.48726e-01        1.41900e-03        1.91423e-01        1.65710e-02       -1.00000e-05        8.15600e-03 
15.68966        1.09657e+00        -1.09067e+00        1.76430e-01        1.34400e-03        2.22657e-01        1.56180e-02       -9.00000e-06        8.50600e-03 
16.72414        1.11040e+00        -1.10441e+00        2.02883e-01        1.26100e-03        2.52158e-01        1.43276e-02       -9.00000e-06        8.80900e-03 
17.75862        1.12290e+00        -1.11682e+00        2.29606e-01        1.20600e-03        2.81695e-01        1.35432e-02       -8.00000e-06        9.07600e-03 
18.79310        1.13461e+00        -1.12844e+00        2.55478e-01        1.15500e-03        3.10143e-01        1.28744e-02       -8.00000e-06        9.34700e-03 
19.82759        1.14605e+00        -1.13974e+00        2.80923e-01        1.08200e-03        3.37970e-01        1.16844e-02       -8.00000e-06        9.61200e-03 
20.86207        1.15722e+00        -1.15073e+00        3.05117e-01        1.03800e-03        3.64240e-01        1.10866e-02       -7.00000e-06        9.87000e-03 
21.89655        1.16808e+00        -1.16138e+00        3.27770e-01        9.81000e-04        3.88826e-01        1.02373e-02       -7.00000e-06        1.01370e-02 
22.93103        1.17845e+00        -1.17148e+00        3.48909e-01        9.33000e-04        4.11299e-01        9.52780e-03       -7.00000e-06        1.03870e-02 
23.96552        1.18930e+00        -1.18205e+00        3.70277e-01        8.93000e-04        4.34300e-01        9.01762e-03       -7.00000e-06        1.06550e-02 
25.00000        1.19987e+00        -1.19227e+00        3.90503e-01        8.36000e-04        4.55921e-01        8.12755e-03       -7.00000e-06        1.09080e-02 
1.00        -  Re
aoa             Ue_Vinf_SS          Ue_Vinf_PS         Dstar_SS           Dstar_PS           Delta_SS           Delta_PS           Cf_SS              Cf_PS
(deg)           (-)                 (-)                (-)                (-)                (-)                (-)                (-)                (-)
-5.00000        8.34300e-01        -8.32480e-01        6.49600e-03        7.74600e-03        2.28566e-02        3.97467e-02        8.39000e-04        1.54900e-03 
-3.96552        8.37330e-01        -8.35790e-01        7.10100e-03        6.55800e-03        2.45059e-02        3.67266e-02        7.84000e-04        1.80000e-03 
-2.93103        8.40670e-01        -8.39370e-01        7.75600e-03        5.65600e-03        2.62162e-02        3.42658e-02        7.27000e-04        2.03700e-03 
-1.89655        8.44170e-01        -8.43070e-01        8.45300e-03        4.96000e-03        2.79616e-02        3.22259e-02        6.72000e-04        2.25700e-03 
-0.86207        8.47840e-01        -8.46890e-01        9.21600e-03        4.45100e-03        2.98142e-02        3.07238e-02        6.18000e-04        2.45400e-03 
 0.17241        8.51730e-01        -8.50900e-01        1.00790e-02        3.95100e-03        3.18738e-02        2.89503e-02        5.65000e-04        2.66300e-03 
 1.20690        8.55470e-01        -8.54730e-01        1.09340e-02        3.54400e-03        3.37289e-02        2.74209e-02        5.12000e-04        2.86100e-03 
 2.24138        8.59040e-01        -8.58320e-01        1.18130e-02        3.25200e-03        3.55603e-02        2.64490e-02        4.62000e-04        3.03800e-03 
 3.27586        8.63480e-01        -8.62770e-01        1.29500e-02        2.91700e-03        3.78947e-02        2.47691e-02        4.08000e-04        3.23200e-03 
 4.31034        8.67590e-01        -8.66830e-01        1.40320e-02        2.69800e-03        3.97441e-02        2.39342e-02        3.50000e-04        3.40400e-03 
 5.34483        8.72380e-01        -8.71540e-01        1.53110e-02        2.43000e-03        4.18407e-02        2.22446e-02        2.92000e-04        3.59200e-03 
 6.37931        8.78360e-01        -8.77360e-01        1.68420e-02        2.23600e-03        4.38267e-02        2.12352e-02        2.20000e-04        3.78300e-03 
 7.41379        8.86030e-01        -8.84810e-01        1.87390e-02        2.00100e-03        4.60113e-02        1.94428e-02        1.44000e-04        4.00100e-03 
 8.44828        8.96310e-01        -8.94850e-01        2.13480e-02        1.83100e-03        4.88127e-02        1.83696e-02        5.90000e-05        4.24200e-03 
 9.48276        9.25990e-01        -9.23230e-01        2.81520e-02        1.56900e-03        5.51012e-02        1.62260e-02       -1.00000e-06        4.73700e-03 
10.51724        9.66170e-01        -9.62320e-01        4.28900e-02        1.36700e-03        7.03103e-02        1.45187e-02       -9.00000e-06        5.34800e-03 
11.55172        1.00255e+00        -9.97860e-01        6.33540e-02        1.21700e-03        9.26255e-02        1.29836e-02       -7.00000e-06        5.90200e-03 
12.58621        1.03100e+00        -1.02578e+00        8.62500e-02        1.10600e-03        1.18923e-01        1.16999e-02       -6.00000e-06        6.34900e-03 
13.62069        1.05406e+00        -1.04857e+00        1.10634e-01        1.04100e-03        1.47132e-01        1.09721e-02       -6.00000e-06        6.70700e-03 
14.65517        1.07334e+00        -1.06769e+00        1.35720e-01        9.66000e-04        1.76016e-01        9.96935e-03       -5.00000e-06        7.01900e-03 
15.68966        1.08881e+00        -1.08308e+00        1.60129e-01        9.17000e-04        2.03832e-01        9.33244e-03       -5.00000e-06        7.27400e-03 
16.72414        1.10158e+00        -1.09579e+00        1.83765e-01        8.82000e-04        2.30423e-01        8.89329e-03       -5.00000e-06        7.49000e-03 
17.75862        1.11342e+00        -1.10758e+00        2.08205e-01        8.32000e-04        2.57695e-01        8.20477e-03       -4.00000e-06        7.69800e-03 
18.79310        1.12407e+00        -1.11817e+00        2.32504e-01        8.01000e-04        2.84583e-01        7.81234e-03       -4.00000e-06        7.88600e-03 
19.82759        1.13501e+00        -1.12904e+00        2.57953e-01        7.76000e-04        3.12682e-01        7.52201e-03       -4.00000e-06        8.07500e-03 
20.86207        1.14614e+00        -1.14008e+00        2.83630e-01        7.33000e-04        3.41005e-01        6.90325e-03       -4.00000e-06        8.27100e-03 
21.89655        1.15868e+00        -1.15248e+00        3.10888e-01        7.07000e-04        3.71055e-01        6.60979e-03       -4.00000e-06        8.48600e-03 
22.93103        1.17050e+00        -1.16410e+00        3.35623e-01        6.81000e-04        3.98279e-01        6.28286e-03       -3.00000e-06        8.69100e-03 
23.96552        1.18348e+00        -1.17683e+00        3.61314e-01        6.45000e-04        4.26528e-01        5.81057e-03       -3.00000e-06        8.91700e-03 
25.00000        1.19753e+00        -1.19058e+00        3.87323e-01        6.21000e-04        4.54991e-01        5.52432e-03       -3.00000e-06        9.15800e-03 
5.00        -  Re
aoa             Ue_Vinf_SS          Ue_Vinf_PS         Dstar_SS           Dstar_PS           Delta_SS           Delta_PS           Cf_SS              Cf_PS
(deg)           (-)                 (-)                (-)                (-)                (-)                (-)                (-)                (-)
-5.00000        8.23420e-01        -8.21880e-01        4.67200e-03        4.76700e-03        1.77334e-02        2.96859e-02        6.92000e-04        1.41000e-03 
-3.96552        8.25550e-01        -8.24400e-01        5.04400e-03        4.14000e-03        1.88321e-02        2.75480e-02        6.57000e-04        1.55000e-03 
-2.93103        8.27930e-01        -8.27220e-01        5.46200e-03        3.53900e-03        2.00407e-02        2.52464e-02        6.21000e-04        1.70500e-03 
-1.89655        8.30490e-01        -8.30120e-01        5.91700e-03        3.10400e-03        2.13254e-02        2.34284e-02        5.86000e-04        1.84000e-03 
-0.86207        8.33100e-01        -8.33000e-01        6.40000e-03        2.77600e-03        2.26264e-02        2.19701e-02        5.50000e-04        1.95800e-03 
 0.17241        8.35520e-01        -8.35690e-01        6.86100e-03        2.45300e-03        2.37731e-02        2.03359e-02        5.15000e-04        2.08300e-03 
 1.20690        8.38270e-01        -8.38660e-01        7.40600e-03        2.17500e-03        2.51176e-02        1.87906e-02        4.79000e-04        2.20700e-03 
 2.24138        8.41350e-01        -8.41880e-01        8.04900e-03        1.95800e-03        2.66635e-02        1.75032e-02        4.40000e-04        2.31900e-03 
 3.27586        8.43950e-01        -8.44520e-01        8.65200e-03        1.80300e-03        2.79650e-02        1.65339e-02        4.03000e-04        2.40900e-03 
 4.31034        8.48180e-01        -8.48810e-01        9.58300e-03        1.61000e-03        3.00737e-02        1.51804e-02        3.59000e-04        2.53200e-03 
 5.34483        8.53570e-01        -8.54090e-01        1.08300e-02        1.48600e-03        3.27612e-02        1.43249e-02        3.08000e-04        2.63700e-03 
 6.37931        8.72880e-01        -8.73060e-01        1.51570e-02        1.28200e-03        4.16833e-02        1.28096e-02        1.92000e-04        2.88700e-03 
 7.41379        8.92130e-01        -8.91760e-01        1.98220e-02        1.14700e-03        4.87740e-02        1.17767e-02        8.30000e-05        3.11600e-03 
 8.44828        9.17360e-01        -9.16020e-01        2.50640e-02        9.92000e-04        5.31945e-02        1.04181e-02        2.00000e-06        3.41900e-03 
 9.48276        9.42910e-01        -9.40410e-01        3.17040e-02        8.85000e-04        5.85499e-02        9.42477e-03       -1.00000e-06        3.70700e-03 
10.51724        9.64800e-01        -9.61630e-01        4.02300e-02        7.96000e-04        6.64893e-02        8.47323e-03       -2.00000e-06        3.96100e-03 
11.55172        9.86420e-01        -9.82570e-01        5.11880e-02        7.23000e-04        7.76623e-02        7.65452e-03       -2.00000e-06        4.20700e-03 
12.58621        1.00657e+00        -1.00210e+00        6.43270e-02        6.71000e-04        9.20001e-02        7.06023e-03       -2.00000e-06        4.43100e-03 
13.62069        1.02475e+00        -1.01984e+00        7.93340e-02        6.16000e-04        1.09051e-01        6.35528e-03       -1.00000e-06        4.64000e-03 
14.65517        1.04370e+00        -1.03850e+00        9.84840e-02        5.79000e-04        1.31195e-01        5.91001e-03       -1.00000e-06        4.84500e-03 
15.68966        1.06004e+00        -1.05467e+00        1.18503e-01        5.43000e-04        1.54410e-01        5.44594e-03       -1.00000e-06        5.02500e-03 
16.72414        1.07448e+00        -1.06905e+00        1.39604e-01        5.14000e-04        1.78759e-01        5.05912e-03       -1.00000e-06        5.18500e-03 
17.75862        1.08720e+00        -1.08175e+00        1.61656e-01        4.93000e-04        2.03997e-01        4.79726e-03       -1.00000e-06        5.32500e-03 
18.79310        1.09867e+00        -1.09324e+00        1.84226e-01        4.68000e-04        2.29525e-01        4.45243e-03       -1.00000e-06        5.45500e-03 
19.82759        1.10970e+00        -1.10430e+00        2.08500e-01        4.51000e-04        2.56774e-01        4.24858e-03       -1.00000e-06        5.57800e-03 
20.86207        1.11936e+00        -1.11397e+00        2.32097e-01        4.34000e-04        2.83065e-01        4.03443e-03       -1.00000e-06        5.69000e-03 
21.89655        1.12815e+00        -1.12274e+00        2.54679e-01        4.14000e-04        3.07965e-01        3.77358e-03       -1.00000e-06        5.79400e-03 
22.93103        1.13774e+00        -1.13227e+00        2.78750e-01        4.00000e-04        3.34530e-01        3.60784e-03       -1.00000e-06        5.90600e-03 
23.96552        1.14721e+00        -1.14164e+00        3.02299e-01        3.84000e-04        3.60352e-01        3.41109e-03       -1.00000e-06        6.01800e-03 
25.00000        1.15816e+00        -1.15244e+00        3.27151e-01        3.68000e-04        3.87710e-01        3.21949e-03       -1.00000e-06        6.14600e-03 
10.00       -  Re
aoa             Ue_Vinf_SS          Ue_Vinf_PS         Dstar_SS           Dstar_PS           Delta_SS           Delta_PS           Cf_SS              Cf_PS
(deg)           (-)                 (-)                (-)                (-)                (-)                (-)                (-)                (-)
-5.00000        8.19760e-01        -8.18060e-01        4.17800e-03        4.54900e-03        1.65706e-02        2.88150e-02        6.56000e-04        1.23100e-03 
-3.96552        8.21540e-01        -8.20450e-01        4.52500e-03        3.74000e-03        1.76308e-02        2.59028e-02        6.23000e-04        1.39100e-03 
-2.93103        8.23580e-01        -8.22970e-01        4.89400e-03        3.21700e-03        1.87333e-02        2.38284e-02        5.91000e-04        1.51700e-03 
-1.89655        8.25560e-01        -8.25320e-01        5.25400e-03        2.85300e-03        1.97567e-02        2.22669e-02        5.60000e-04        1.62100e-03 
-0.86207        8.27870e-01        -8.28060e-01        5.67900e-03        2.46600e-03        2.09522e-02        2.03860e-02        5.28000e-04        1.74400e-03 
 0.17241        8.30330e-01        -8.30840e-01        6.14400e-03        2.18100e-03        2.22219e-02        1.88758e-02        4.96000e-04        1.84900e-03 
 1.20690        8.32880e-01        -8.33650e-01        6.64800e-03        1.94100e-03        2.35312e-02        1.74735e-02        4.63000e-04        1.94900e-03 
 2.24138        8.35130e-01        -8.36090e-01        7.13000e-03        1.75100e-03        2.46910e-02        1.62700e-02        4.31000e-04        2.03800e-03 
 3.27586        8.39970e-01        -8.41060e-01        8.09900e-03        1.56800e-03        2.72181e-02        1.50508e-02        3.88000e-04        2.14300e-03 
 4.31034        8.50470e-01        -8.51560e-01        1.01990e-02        1.37300e-03        3.25448e-02        1.36378e-02        3.18000e-04        2.29400e-03 
 5.34483        8.64450e-01        -8.65280e-01        1.32660e-02        1.23700e-03        3.92329e-02        1.26866e-02        2.31000e-04        2.45100e-03 
 6.37931        8.78610e-01        -8.79110e-01        1.65810e-02        1.08900e-03        4.49765e-02        1.14397e-02        1.47000e-04        2.62200e-03 
 7.41379        8.91030e-01        -8.91080e-01        1.96290e-02        9.93000e-04        4.89936e-02        1.06282e-02        7.60000e-05        2.76500e-03 
 8.44828        9.08900e-01        -9.08620e-01        2.35230e-02        8.71000e-04        5.22284e-02        9.45732e-03        2.00000e-06        2.96800e-03 
 9.48276        9.32700e-01        -9.30700e-01        2.84210e-02        7.79000e-04        5.52443e-02        8.61055e-03       -0.00000e+00        3.20000e-03 
10.51724        9.51380e-01        -9.48770e-01        3.46600e-02        6.96000e-04        6.05165e-02        7.64709e-03       -1.00000e-06        3.39700e-03 
11.55172        9.71740e-01        -9.68450e-01        4.35850e-02        6.37000e-04        6.90670e-02        6.98615e-03       -1.00000e-06        3.59500e-03 
12.58621        9.91260e-01        -9.87290e-01        5.44080e-02        5.84000e-04        8.03205e-02        6.33577e-03       -1.00000e-06        3.78700e-03 
13.62069        1.00996e+00        -1.00542e+00        6.74960e-02        5.36000e-04        9.47613e-02        5.73102e-03       -1.00000e-06        3.97000e-03 
14.65517        1.02771e+00        -1.02275e+00        8.31660e-02        5.06000e-04        1.12645e-01        5.35979e-03       -1.00000e-06        4.13700e-03 
15.68966        1.04427e+00        -1.03905e+00        1.00836e-01        4.71000e-04        1.33082e-01        4.88548e-03       -1.00000e-06        4.29600e-03 
16.72414        1.06019e+00        -1.05485e+00        1.21136e-01        4.45000e-04        1.56673e-01        4.55077e-03       -1.00000e-06        4.44600e-03 
17.75862        1.07407e+00        -1.06868e+00        1.42220e-01        4.22000e-04        1.81035e-01        4.24533e-03       -1.00000e-06        4.57900e-03 
18.79310        1.08623e+00        -1.08087e+00        1.64037e-01        4.01000e-04        2.06006e-01        3.94306e-03       -0.00000e+00        4.69600e-03 
19.82759        1.09748e+00        -1.09215e+00        1.87080e-01        3.86000e-04        2.32142e-01        3.76503e-03       -0.00000e+00        4.80500e-03 
20.86207        1.10794e+00        -1.10267e+00        2.10804e-01        3.67000e-04        2.58816e-01        3.50553e-03       -0.00000e+00        4.90800e-03 
21.89655        1.11776e+00        -1.11253e+00        2.35256e-01        3.54000e-04        2.86067e-01        3.34709e-03       -0.00000e+00        5.00500e-03 
22.93103        1.12664e+00        -1.12138e+00        2.58366e-01        3.43000e-04        3.11568e-01        3.20986e-03       -0.00000e+00        5.09600e-03 
23.96552        1.13635e+00        -1.13106e+00        2.83067e-01        3.28000e-04        3.38816e-01        3.02058e-03       -0.00000e+00        5.19400e-03 
25.00000        1.14573e+00        -1.14034e+00        3.06604e-01        3.16000e-04        3.64612e-01        2.86692e-03       -0.00000e+00        5.29100e-03 

4.4.7.3. Observer Positions

The number and position of observers is set in the file ObserverLocations, which is explained in Section 4.4.7.1. The positions must be specified in the OpenFAST global inertial frame coordinate system, which is located at the tower base and has the x-axis pointing downwind, the y-axis pointing laterally, and the z-axis pointing vertically upward. A scheme of the coordinate system for the observers is shown in Fig. 4.20.

Reference system for the observers

Fig. 4.20 Reference system for the observers

The International Energy Agency Wind Task 37 land-based reference wind turbine, which is shown in Table 4.2, has a hub height of 110 meters and a rotor radius of 65 meters, and has the International Electrotechnical Commission 61400-11 standards compliant observer located at:

x = 175 [m]

y = 0 [m]

z = 0 [m].

An example of a file listing four observers located at a 2-meter height is shown here:

1
2
3
4
5
6
4 NrObsLoc - Total Number of observer locations
X Observer location in tower-base coordinate X horizontal (m), Y Observer location in tower-base coordinate Y Lateral (m), Z Observer location in tower-base coordinate Z Vertical (m)
-200  -200  2
-200  +200  2
+200  -200  2
+200  +200  2

4.4.7.4. Turbulence Grid

When the flag TICalcMeth is set equal to 1, the grid of incident turbulent intensity \(I_{1}\) must be defined by the user. This is done by creating a file called TIGrid_In.txt, which mimics a TurbSim output file and contains a grid of turbulence intensity, which is defined as a fraction value. The file defines a grid centered at hub height and oriented with the OpenFAST global inertial frame coordinate system; see Fig. 4.20. A user-defined number of lateral and vertical points equally spaced by a user-defined number of meters must be specified. An example file for a 160 (lateral) by 180 (vertical) meters grid looks like the following:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
Total Grid points In Y (lateral), Starts from - radius goes to + radius+
4
Total Grid points In Z (vertical), Starts from bottom tip (hub-radius)
3
Grid spacing In Y (lateral)
40
Grid spacing In Z (vertical)
60
0.1200 0.1200 0.1200 0.1200
0.1100 0.1100 0.1100 0.1100
0.1000 0.1000 0.1000 0.1000

4.4.7.5. Trailing-Edge Geometry

When the flag BluntMod is set to 1, the detailed geometry of the trailing edge must be defined along the span. Two inputs must be provided, namely the angle, \(\Psi,\) between the suction and pressure sides of the profile, right before the trailing-edge point, and the height, \(h\), of the trailing edge. \(\Psi\) must be defined in degrees, while \(h\) is in meters. Note that the BPM trailing-edge bluntness model is very sensitive to these two parameters, which, however, are often not easy to determine for real blades. Fig. 4.21 shows the two inputs.

Geometric parameters of the trailing-edge bluntness

Fig. 4.21 Geometric parameters \(\mathbf{\Psi}\) and \(\mathbf{h}\) of the trailing-edge bluntness

The two distributions must be defined with the same spanwise resolution of the AeroDyn15 blade file, such as:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Example aerodynamic blade input properties
====== Blade Properties ==========================================
30    NumBlNds    - Number of blade nodes used in the analysis (-)
TEAngle              TEThick
(deg)                (m)
10.000000E+00        0.03000E+00
10.000000E+00        0.02900E+00
10.000000E+00        0.02800E+00
10.000000E+00        0.02700E+00
10.000000E+00        0.02600E+00
10.000000E+00        0.02500E+00
10.000000E+00        0.02400E+00
10.000000E+00        0.02300E+00
10.000000E+00        0.02200E+00
10.000000E+00        0.02100E+00
10.000000E+00        0.02000E+00
10.000000E+00        0.01900E+00
10.000000E+00        0.01800E+00
10.000000E+00        0.01700E+00
10.000000E+00        0.01600E+00
10.000000E+00        0.01500E+00
10.000000E+00        0.01400E+00
10.000000E+00        0.01300E+00
10.000000E+00        0.01200E+00
10.000000E+00        0.01100E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
10.000000E+00        0.01000E+00
4

https://github.com/OpenFAST/python-toolbox