Dynamic Analysis of offshore wind turbine on triceratop floating platform

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Purushotham.Chinu
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Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Tue Feb 21, 2017 7:39 pm

Dear Jason,

i have modelled my floater in ansys aqwa which is a new age floating platform, which has a equilateral triangle shaped deck and connected with three bls units(taut moored spars) connected through ball and socket joint and the bls units are in turn connected to the seabed,sice there is no test file available in fast for this platform, i am unable to understand how can i couple ansys aqwa with fast to carry out fully coupled aero-hydrodynamic analysis,and since i am not aware of the procedure to couple aqwa with fast,kindly guide me in this aspect.

regards

purushotham

Jason.Jonkman
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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Wed Feb 22, 2017 6:05 pm

Dear Purushotham,

What sort of FAST - ANSYS/AQWA coupling are you envisioning?

If you simply want to take the frequency-dependent hydrodynamic coefficients computed by AQWA and use them in FAST/HydroDyn, you will simply need to convert the format to that of WAMIT, and perhaps shift the reference point as discussed in the following forum topic: viewtopic.php?f=13&t=981&p=4152.

If you want to develop some sort of two-way structure-to-structure coupling between FAST and ANSYS/AQWA, that is a much more involved task.

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

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Wed Feb 22, 2017 9:28 pm

Dear Jason,

Thanks a lot for quick reply, i would just like to know is it possible to create a test file for the triceratop floating platform,and also jason i am unaware of the method to convert aqwa to wamit format , and also since the soul of my platform is ball joints between the deck and the bls units which are quiet difficult to be modelled in wamit, i would like to know how this coupling can be done, like the sole objective of my work is to find the effect(in terms ofresponses) due to the wind turbine on the platform and vice versa in all six degrees of freedom and thereby prove how my platform is much better compared to the other floating platforms,kindly guide me in this aspect and if you can provide me with the test file for the triceratop it will be of great help.


regards

purushotham

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Thu Feb 23, 2017 7:12 am

Dear jason,

Also could you elaborate the more involved approach that is the structure to structure coupling between fast and aqwa, kindly reply on the step by step procedure to convert aqwa file format to wamit file format,kindly reply as soon as possible.

regards

Jason.Jonkman
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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Thu Feb 23, 2017 7:47 am

Dear Purushotham,

I’m not sure whether ANSYS/AQWA can directly output to the WAMIT format needed by FAST’s HydroDyn module, but if not, it should not be hard to convert to WAMIT output format yourself—the format of the WAMIT-generated output files (*.1, *.3, and *.hst for first order, etc.) needed by HydroDyn can be found in Chapter 4 of the WAMIT User’s Manual, available online: http://www.wamit.com/manual6.4/Chap4.pdf.

However, FAST itself does not have any structural degrees of freedom (DOFs) to represent the ball joints of your concept. I see a few paths forward:
1) Model the platform with the ball joints fixed i.e. a rigid platform model.
2) Modify the FAST source code to introduce the DOFs you need.
3) Develop a structure-to-structure coupling between FAST and e.g. ANSYS/AQWA.

Option (1) can be set up with the existing FAST software, without modification of the source code, but may not give you satisfactory results. Options (2) and (3) will both take a significant level of effort and NREL doesn't have the resources to provide a detailed step-by-step process toward their implementation.

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

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Thu Feb 23, 2017 5:23 pm

Dear Jason,

I would like to know if inputting the forces from fast in all six degrees of freedom as a structure force in ansys aqwa will help me in ggetting the coupling effect besides for that i have taken yawbr force components and inptted that into aqwa to get the time responses in all six degrees of freedom, and also is there a way we can establish a simlitude between tlp and triceratop as the fundamental diff between them is the ball joints and modify the fast source code,also jason how can i find the natural frequencies of the entire system in fast. and also i am not toable to find methods for converting aqwa format to wamit format ,please elaborately guide me with sources for it.


regards

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Fri Feb 24, 2017 12:50 am

D ear Jason,

I wish to study the effect of the wind speeds on the responses of the platform what is the procedure to change the wind speed , and will that have any effect on the yawbr forces so that i can input it for different time steps in aqwa also jason i am getting the following error when i am running it for 600 seconds, it shows inflow wind with coordinates with error: ff wind, kindly let me know how can i solve this problem.

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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Fri Feb 24, 2017 10:06 am

Dear Purushotham,

Taking the tower-top or tower-base loads from FAST and inputting them into an FEA model is generally not recommend as has been discussed recently on the forum--see e.g. my post dated Feb 23, 2017 in the following forum topic: viewtopic.php?f=4&t=1778.

I'm not sure I can offer advice on establishing similitude between a TLP and your platform. You should establish your own modeling assumptions for your own purposes.

For fixed-bottom systems, the linearization function of FAST v8 can be used to derive the natural frequencies and mode shapes of parked or operational turbine--see e.g. viewtopic.php?f=3&t=1056. We don't yet have linearization functionality in FAST v8 for floating systems, which makes deriving natural frequencies for these systems a bit more difficult, as discussed in the following forum topic: viewtopic.php?f=4&t=475&p=8098.

I gave a link to the WAMIT format above, so, as long as you understand the AQWA format, you should be able to write a converter between them. I don't know anything about the AQWA format, so, I can't comment further.

Changing the wind speed requires you to change the wind data in the InflowWind module of FAST, as well as setting proper initial conditions e.g. rotor speed and pitch angle, as has been discussed many times on this forum.

An error regarding the "FF wind array was exhausted" has been discussed many times on this forum e.g.: viewtopic.php?f=4&t=1450&p=8249.

Please use "search..." in the upper-right corner before asking questions. NREL can't offer unlimited support to free open-source software.

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

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Mon Feb 27, 2017 12:41 am

Dear jason,

As guided by you i have generated the wind file by turbsim but now i am getting a different error, saying that FFWind_calcoutput[position=(0,0,0) in wind file coordinates: FF wind array boundaries violated. grid too small in z direction(z=0) is below the grid and no tower points are defined, kindly give me a solution for this problem, kindly reply.

regards

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Mon Feb 27, 2017 1:29 am

Dear jason,

when i run turbsim , it is sucessfully terminated but shows the warning tower output time series will be turned off as there are no extra data points below the grid, kindly enlighten me on this aspect,

regards

purushotham

Jason.Jonkman
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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Mon Feb 27, 2017 6:51 am

Dear Purushotham,

That warning message is just telling you that TurbSim has not generated wind data along the tower because you've set your grid low enough (near the ground) so that tower points are not needed.

After generating this wind data, is FAST now running for you?

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

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Mon Feb 27, 2017 7:30 am

Dear Jason,

As guided by you i have generated the wind file by turbsim but now i am getting a different error, saying that FFWind_calcoutput[position=(0,0,0) in wind file coordinates: FF wind array boundaries violated. grid too small in z direction(z=0) is below the grid and no tower points are defined, kindly give me a solution for this problem, kindly reply.

regards

Jason.Jonkman
Posts: 5882
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Mon Feb 27, 2017 10:30 am

Dear Puroshotham,

As far as I can tell, you've generated wind data in TurbSim for a grid that reaches very close to the ground, and you haven't generated wind data along the tower, but you've placed an aerodynamic node in AeroDyn at ground level, below the TurbSim grid. You must ensure that the wind data extends beyond where you'd like to compute aerodynamic loads. If your TurbSim grid starts just above the ground, make sure that you don't have aerodynamic nodes lower than the bottom of the grid.

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

Purushotham.Chinu
Posts: 39
Joined: Tue Feb 21, 2017 7:37 am
Organization: IITM
Location: India

Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Purushotham.Chinu » Mon Feb 27, 2017 5:00 pm

Dear Jason,

I guess what you are trying to say that my turbsim file is incompatible with the aerodyn file of my model, i am sending my aerodyn input and wind input file, kindly tell me what is wrong with it as i tried a lot but not achieving any success.

AEODYN INPUT FILE

------- AERODYN v15.03.* INPUT FILE ------------------------------------------------
NREL 5.0 MW offshore baseline aerodynamic input properties.
====== General Options ============================================================================
False Echo - Echo the input to "<rootname>.AD.ech"? (flag)
"default" DTAero - 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) {1=steady model, 2=Beddoes-Leishman unsteady model}
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}
False TwrShadow – Calculate tower influence on wind based on downstream tower shadow? (flag)
True TwrAero - Calculate tower aerodynamic loads? (flag)
False FrozenWake - Assume frozen wake during linearization? (flag) [used only when WakeMod=1 and when linearizing]
====== Environmental Conditions ===================================================================
1.225 AirDens - Air density (kg/m^3)
1.464E-05 KinVisc - Kinematic air viscosity (m^2/s)
335 SpdSound - Speed of sound (m/s)
====== Blade-Element/Momentum Theory Options ====================================================== [used only when WakeMod=1]
2 SkewMod - Type of skewed-wake correction model (switch) {1=uncoupled, 2=Pitt/Peters, 3=coupled} [used only when WakeMod=1]
True TipLoss - Use the Prandtl tip-loss model? (flag) [used only when WakeMod=1]
True HubLoss - Use the Prandtl hub-loss model? (flag) [used only when WakeMod=1]
true TanInd - Include tangential induction in BEMT calculations? (flag) [used only when WakeMod=1]
False AIDrag - Include the drag term in the axial-induction calculation? (flag) [used only when WakeMod=1]
False TIDrag - Include the drag term in the tangential-induction calculation? (flag) [used only when WakeMod=1 and TanInd=TRUE]
"Default" IndToler - Convergence tolerance for BEMT nonlinear solve residual equation {or "default"} (-) [used only when WakeMod=1]
100 MaxIter - Maximum number of iteration steps (-) [used only when WakeMod=1]
====== Beddoes-Leishman Unsteady Airfoil Aerodynamics Options ===================================== [used only when AFAeroMod=2]
3 UAMod - Unsteady Aero Model Switch (switch) {1=Baseline model (Original), 2=Gonzalez’s variant (changes in Cn,Cc,Cm), 3=Minemma/Pierce variant (changes in Cc and Cm)} [used only when AFAeroMod=2]
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 AFAeroMod=2]
====== Airfoil Information =========================================================================
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 (-)
"Airfoils/Cylinder1.dat" AFNames - Airfoil file names (NumAFfiles lines) (quoted strings)
"Airfoils/Cylinder2.dat"
"Airfoils/DU40_A17.dat"
"Airfoils/DU35_A17.dat"
"Airfoils/DU30_A17.dat"
"Airfoils/DU25_A17.dat"
"Airfoils/DU21_A17.dat"
"Airfoils/NACA64_A17.dat"
====== Rotor/Blade Properties =====================================================================
True UseBlCm - Include aerodynamic pitching moment in calculations? (flag)
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(1) - Name of file containing distributed aerodynamic properties for Blade #1 (-)
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(2) - Name of file containing distributed aerodynamic properties for Blade #2 (-) [unused if NumBl < 2]
"NRELOffshrBsline5MW_AeroDyn_blade.dat" ADBlFile(3) - Name of file containing distributed aerodynamic properties for Blade #3 (-) [unused if NumBl < 3]
====== Tower Influence and Aerodynamics ============================================================= [used only when TwrPotent/=0, TwrShadow=True, or TwrAero=True]
12 NumTwrNds - Number of tower nodes used in the analysis (-) [used only when TwrPotent/=0, TwrShadow=True, or TwrAero=True]
TwrElev TwrDiam TwrCd
(m) (m) (-)
0.0000000E+00 6.0000000E+00 1.0000000E+00
8.5261000E+00 5.7870000E+00 1.0000000E+00
1.7053000E+01 5.5740000E+00 1.0000000E+00
2.5579000E+01 5.3610000E+00 1.0000000E+00
3.4105000E+01 5.1480000E+00 1.0000000E+00
4.2633000E+01 4.9350000E+00 1.0000000E+00
5.1158000E+01 4.7220000E+00 1.0000000E+00
5.9685000E+01 4.5090000E+00 1.0000000E+00
6.8211000E+01 4.2960000E+00 1.0000000E+00
7.6738000E+01 4.0830000E+00 1.0000000E+00
8.5268000E+01 3.8700000E+00 1.0000000E+00
8.7600000E+01 3.8700000E+00 1.0000000E+00
====== Outputs ====================================================================================
True SumPrint - Generate a summary file listing input options and interpolated properties to "<rootname>.AD.sum"? (flag)
0 NBlOuts - Number of blade node outputs [0 - 9] (-)
1, 9, 19 BlOutNd - Blade nodes whose values will be output (-)
0 NTwOuts - Number of tower node outputs [0 - 9] (-)
1, 2, 6 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, (-)
END of input file (the word "END" must appear in the first 3 columns of this last OutList line)
---------------------------------------------------------------------------------------

and here is the wind input file(11p4mps.wnd)

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-----------------------------------
2090630798 The first seed
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)
True 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 - Vertical grid-point matrix dimension
31 NumGrid_Y - Horizontal grid-point matrix dimension
0.01 TimeStep - Time step [seconds]
600.0 AnalysisTime - Length of analysis time series [seconds]
10.0 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds)
90.0 HubHt - Hub height [m] (should be > 0.5*GridHeight)
170.0 GridHeight - Grid height [m]
170.0 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]

--------Meteorological Boundary Conditions-------------------
IECKAI TurbModel - Turbulence model ("IECKAI"=Kaimal, "IECVKM"=von Karman, "GP_LLJ", "NWTCUP", "SMOOTH", "WF_UPW", "WF_07D", "WF_14D", or "NONE")
"1-ed3" IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. "1-Ed2") )
"A" IECturbc - IEC turbulence characteristic ("A", "B", "C" or the turbulence intensity in percent) ("KHTEST" option with NWTCUP, not used for other models)
NTM IEC_WindType - IEC turbulence type ("NTM"=normal, "xETM"=extreme turbulence, "xEWM1"=extreme 1-year wind, "xEWM50"=extreme 50-year wind, where x=wind turbine class 1, 2, or 3)
default ETMc - IEC Extreme turbulence model "c" parameter [m/s]
default WindProfileType - Wind profile type ("JET"=Low-level jet,"LOG"=Logarithmic,"PL"=Power law, or "default", or "USR"=User-defined)
87.2876 RefHt - Height of the reference wind speed [m]
11.4 URef - Mean (total) wind speed at the reference height [m/s]
default ZJetMax - Jet height [m] (used only for JET wind profile, valid 70-490 m)
default PLExp - Power law exponent [-] (or "default")
default Z0 - Surface roughness length [m] (or "default")

--------Non-IEC Meteorological Boundary Conditions------------
[0] 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/s)^2] (or "default")
default PC_UV - Hub mean u'v' Reynolds stress [(m/s)^2] (or "default")
default PC_VW - Hub mean v'w' Reynolds stress [(m/s)^2] (or "default")
default IncDec1 - u-component coherence parameters (e.g. "10.0 0.3e-3" in quotes) (or "default")
default IncDec2 - v-component coherence parameters (e.g. "10.0 0.3e-3" in quotes) (or "default")
default IncDec3 - w-component coherence parameters (e.g. "10.0 0.3e-3" in quotes) (or "default")
default CohExp - Coherence exponent (or "default")

--------Coherent Turbulence Scaling Parameters-------------------
"E:\TurbSim_v150\EventData" CTEventPath - Name of the path where event data files are located
"Random" CTEventFile - Type of event files ("random", "les" or "dns")
true Randomize - Randomize disturbance scale and location? (true/false)
1.0 DistScl - Disturbance scale (ratio of dataset height to rotor disk).
0.5 CTLy - Fractional location of tower centerline from right (looking downwind) to left side of the dataset.
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 [seconds]

And here is the inflow wind file where i have called the turbsim file

------- InflowWind v3.01.* INPUT FILE -------------------------------------------------------------------------
12 m/s turbulent winds on 31x31 FF grid and tower for FAST CertTests #18, #19, #21, #22, #23, and #24
---------------------------------------------------------------------------------------------------------------
False Echo - Echo input data to <RootName>.ech (flag)
3 WindType - switch for wind file type (1=steady; 2=uniform; 3=binary TurbSim FF; 4=binary Bladed-style FF; 5=HAWC format; 6=User defined)
0 PropagationDir - Direction of wind propagation (meteoroligical rotation from aligned with X (positive rotates towards -Y) -- degrees)
1 NWindVel - Number of points to output the wind velocity (0 to 9)
0 WindVxiList - List of coordinates in the inertial X direction (m)
0 WindVyiList - List of coordinates in the inertial Y direction (m)
90 WindVziList - List of coordinates in the inertial Z direction (m)
================== Parameters for Steady Wind Conditions [used only for WindType = 1] =========================
10 HWindSpeed - Horizontal windspeed (m/s)
90 RefHt - Reference height for horizontal wind speed (m)
0.2 PLexp - Power law exponent (-)
================== Parameters for Uniform wind file [used only for WindType = 2] ============================
"Wind/90m_12mps_twr.bts" Filename - Filename of time series data for uniform wind field. (-)
90 RefHt - Reference height for horizontal wind speed (m)
125.88 RefLength - Reference length for linear horizontal and vertical sheer (-)
================== Parameters for Binary TurbSim Full-Field files [used only for WindType = 3] ==============
"Wind/11p4mps.bts" Filename - Name of the Full field wind file to use (.bts)
================== Parameters for Binary Bladed-style Full-Field files [used only for WindType = 4] =========
"Wind/90m_12mps_twr" FilenameRoot - Rootname of the full-field wind file to use (.wnd, .sum)
False TowerFile - Have tower file (.twr) (flag)
================== Parameters for HAWC-format binary files [Only used with WindType = 5] =====================
"wasp\Output\basic_5u.bin" FileName_u - name of the file containing the u-component fluctuating wind (.bin)
"wasp\Output\basic_5v.bin" FileName_v - name of the file containing the v-component fluctuating wind (.bin)
"wasp\Output\basic_5w.bin" FileName_w - name of the file containing the w-component fluctuating wind (.bin)
600 nx - number of grids in the x direction (in the 3 files above) (-)
320 ny - number of grids in the y direction (in the 3 files above) (-)
320 nz - number of grids in the z direction (in the 3 files above) (-)
16 dx - distance (in meters) between points in the x direction (m)
3 dy - distance (in meters) between points in the y direction (m)
3 dz - distance (in meters) between points in the z direction (m)
90 RefHt - reference height; the height (in meters) of the vertical center of the grid (m)
------------- Scaling parameters for turbulence ---------------------------------------------------------
1 ScaleMethod - Turbulence scaling method [0 = none, 1 = direct scaling, 2 = calculate scaling factor based on a desired standard deviation]
1 SFx - Turbulence scaling factor for the x direction (-) [ScaleMethod=1]
1 SFy - Turbulence scaling factor for the y direction (-) [ScaleMethod=1]
1 SFz - Turbulence scaling factor for the z direction (-) [ScaleMethod=1]
12 SigmaFx - Turbulence standard deviation to calculate scaling from in x direction (m/s) [ScaleMethod=2]
8 SigmaFy - Turbulence standard deviation to calculate scaling from in y direction (m/s) [ScaleMethod=2]
2 SigmaFz - Turbulence standard deviation to calculate scaling from in z direction (m/s) [ScaleMethod=2]
------------- Mean wind profile parameters (added to HAWC-format files) ---------------------------------
15 URef - Mean u-component wind speed at the reference height (m/s)
2 WindProfile - Wind profile type (0=constant;1=logarithmic,2=power law)
0.2 PLExp - Power law exponent (-) (used for PL wind profile type only)
0.03 Z0 - Surface roughness length (m) (used for LG wind profile type only)
====================== OUTPUT ==================================================
False SumPrint - Print summary data to <RootName>.IfW.sum (flag)
OutList - The next line(s) contains a list of output parameters. See OutListParameters.xlsx for a listing of available output channels, (-)
"Wind1VelX" X-direction wind velocity at point WindList(1)
"Wind1VelY" Y-direction wind velocity at point WindList(1)
"Wind1VelZ" Z-direction wind velocity at point WindList(1)
END of input file (the word "END" must appear in the first 3 columns of this last OutList line)
---------------------------------------------------------------------------------------

Kindly reply as soon as possible

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
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Re: Dynamic Analysis of offshore wind turbine on triceratop floating platform

Postby Jason.Jonkman » Tue Feb 28, 2017 6:32 am

Dear Purushotham,

Yes, your TurbSim grid starts at 5 m above the ground (=HubHt-GridHeight/2), but your first aerodynamic node starts at ground level (TwrElev(1)=0). You should change your TurbSim file so that you either generate wind along the tower (this will require you to increase HubHt-GridHeight/2 so that it is larger than DZ = GridHeight(NumGrid_Z-1)) or raise the first aerodynamic node to be at or above 5 m.

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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