RNA Inertia FASTv7

Discuss theory and modeling of wind-turbine structures.

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Friedrich.Pienkny
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Joined: Mon Jun 15, 2020 6:44 am
Organization: GICON GmbH
Location: Germany

RNA Inertia FASTv7

Postby Friedrich.Pienkny » Thu Jul 16, 2020 3:52 am

Dear Dr. Jonkman,

I try to calculate the moments of inertia for the RNA of an onshore reference turbine (130-3.4MW, see https://www.nrel.gov/docs/fy19osti/73492.pdf). Therfore, I followed the steps described in post viewtopic.php?f=3&t=1945&p=10131. I converted the input files of the WT to the FASTv7-Format.

I created the following files:

130_lin.fst
130_AD.ipt
Blade_NoDamp.dat
Tower_NoDamp.dat
Platform.dat
Linear_130.dat (Control)

When I run the .fst-file I get an AeroDyn error:

Code: Select all

Running NWTC Subroutine Library (v1.07.00b-mlb, 10-Jan-2013).

 Running AeroDyn (v13.00.02a-bjj, 20-Feb-2013).
 Heading of the AeroDyn input file: 1.5 MW baseline aerodynamic parameters for FAST certification
 test #14.
 WARNING:   Error reading from line 4 of the AeroDyn element table.
 WARNING:   Premature end of file while reading line 4 of the AeroDyn element table in file
 "C:\Users\fpi\Downloads\FASTv7-master_linear_custom\FASTv7-master\CertTest\Test_Lin_130\130_AD.ipt."
 Could not initialize AeroDyn.

 Aborting FAST.


I checked the AD.ipt-file but I cannot find the problem.

Code: Select all

3.4 MW onshore reference turbine aerodynamic parameters.
SI                                     SysUnits - System of units for used for input and output [must be SI for FAST] (unquoted string)
STEADY                                 StallMod - Dynamic stall included [BEDDOES or STEADY] (unquoted string)
NO_CM                                  UseCm    - Use aerodynamic pitching moment model? [USE_CM or NO_CM] (unquoted string)
EQUIL                                  InfModel - Inflow model [DYNIN or EQUIL] (unquoted string)
SWIRL                                  IndModel - Induction-factor model [NONE or WAKE or SWIRL] (unquoted string)
   1.0E-6                              AToler   - Induction-factor tolerance (convergence criteria) (-)
PRANDtl                                TLModel  - Tip-loss model (EQUIL only) [PRANDtl, GTECH, or NONE] (unquoted string)
PRANDtl                                HLModel  - Hub-loss model (EQUIL only) [PRANdtl or NONE] (unquoted string)
"12ms.wnd"                             WindFile - Name of file containing wind data (quoted string)
  220.436                              HH       - Wind reference (hub) height [TowerHt+Twr2Shft+OverHang*SIN(ShftTilt)] (m)
   0.0                                 TwrShad  - Tower-shadow velocity deficit (-)
9999.9                                 ShadHWid - Tower-shadow half width (m)
9999.9                                 T_Shad_Refpt - Tower-shadow reference point (m)
   1.225                               AirDens  - Air density (kg/m^3)
   1.4639E-5                           KinVisc  - Kinematic air viscosity (m^2/sec)
   0.005                               DTAero   - Time interval for aerodynamic calculations (sec)
   30                                  NumFoil  - Number of airfoil files (-)
"Airfoils/Cylinder1.dat"    FoilNm   - Names of the airfoil files [NumFoil lines] (quoted strings)
"Airfoils/DU21_A17.dat"
"Airfoils/DU35_A17.dat"
"Airfoils/DU40_A17.dat"
  29                                   BldNodes - Number of blade nodes used for analysis (-)
RNodes    AeroTwst  DRNodes  Chord  NFoil  PrnElm
 0.63000  19.86     1.26000  2.600  1      NOPRINT
 2.52000  19.16     2.52000  2.740  2      NOPRINT
 5.04000  17.77     2.52000  3.090  2      NOPRINT
 7.47000  15.98     2.34000  3.490  2      NOPRINT
 9.81000  14.02     2.35000  3.880  2      NOPRINT
12.17000  12.02     2.35000  4.180  2      NOPRINT
14.47000  10.19     2.25000  4.290  2      NOPRINT
16.71000   8.54     2.25000  4.250  2      NOPRINT
18.96000   6.91     2.25000  4.150  2      NOPRINT
21.16000   5.36     2.15000  4.010  2      NOPRINT
23.31000   4.08     2.15000  3.860  2      NOPRINT
25.46000   3.15     2.15000  3.690  2      NOPRINT
27.61000   2.50     2.15000  3.460  2      NOPRINT
29.76000   1.98     2.15000  3.200  2      NOPRINT
31.91000   1.54     2.15000  2.940  3      NOPRINT
33.96000   1.18     1.95000  2.760  3      NOPRINT
35.91000   0.87     1.95000  2.590  3      NOPRINT
37.85000   0.61     1.95000  2.430  3      NOPRINT
39.80000   0.37     1.95000  2.290  3      NOPRINT
41.75000   0.15     1.95000  2.170  3      NOPRINT
43.68000  -0.07     1.92000  2.090  3      NOPRINT
45.60000  -0.28     1.92000  2.030  3      NOPRINT
47.52000  -0.46     1.92000  1.990  3      NOPRINT
49.44000  -0.64     1.92000  1.950  3      NOPRINT
51.42000  -0.86     2.03000  1.890  3      NOPRINT
53.45000  -1.17     2.03000  1.770  4      NOPRINT
55.48000  -1.62     2.03000  1.540  4      NOPRINT
57.86000  -2.40     2.73000  1.060  4      NOPRINT
61.11000  -3.77     3.78000  0.200  4      NOPRINT


Regarding the error message, I am not sure what is meant by "AeroDyn element table". I assume it is the table at the end of the file? I hope my desription is sufficient to comprehend the problem.

Thank you very much in advance!

Jason.Jonkman
Posts: 4933
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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Re: RNA Inertia FASTv7

Postby Jason.Jonkman » Mon Jul 20, 2020 7:26 am

Dear Friedrich,

I think the error is that you've specified that there are 30 airfoil files (NumFoil = 30), but you've only identified 4 of them. Perhaps you want to set NumFoil = 4?

That said, you shouldn't need to convert a model into FAST v7 format in order to get calculate the moments of inertia of the RNA. You can use the linearization functionality in newer versions of FAST/OpenFAST for that. The FAST v8 and OpenFAST linearizations do not show the mass matrix directly, but this matrix can often be inferred from other matrices generated through the linearization process. A similar question was asked and answered in the following forum topic: viewtopic.php?f=4&t=2487&p=14535.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


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