Wind Veer Parameter

Hi, I am trying to recreate the following study for a turbine at SWiFT:

“Assessment of Wind Parameter Sensitivity on Ultimate and Fatigue Wind Turbine Loads: Robertson, Sethuraman, Jonkman, Quick (2018)”.

I will be using TurbSim → OpenFAST and examining different parameters than those in the above study, but I did want to examine veer (β in the paper). I grepped all the input files and found nothing. I also didn’t find anything in the TurbSim Manual. How can I change the veer for these simulations?

Thanks!
-Abhi

Dear Abhi,

In TurbSim v2 and TurbSim within OpenFAST, the veer (change in wind direction with height) can be specified using the user-defined wind profile option (WindProfileType=“USR”).

Best regards,

Hi @Jason.Jonkman:
I see there is a forum about veer so I will query this and other things about TurbSim here.
I would like to enter:

  • User defined wind veer profile and wind shear profile

I see where you can enter wind profile using USR and then stating the name of the file that contains the information. These are my queries

  1. For the veer profile, should file contain wind elevation vs wind direction in csv format without any headers?
  2. How is this done for the shear profile, should it be elevation vs wind speed in csv format without headers, if so, where would I enter the information for shear profile?
  3. It is possible to view/plot the graph of the wind power spectrum (IECKAI, for e.g.) after the simulation is complete?
  4. Is it possible to plot a profile of the correlation coefficient for a specified coherence exponent?

I am trying to define wind field parameters for a hurricane as seen in a paper by Kapoor et al (2020).

Thank you.

Regards,
AOAW

Hi @Jason.Jonkman:
I found an example of how to enter wind data. If I understand correctly the wind speed and direction at each elevation is entered in same file. This will take care of shear and veer, where the wind direction represents the veer. Is that correct?
I realize in said file that they have values for standard deviation and length scale at each elevation. However, I do not have such values from data that I am using, only wind speed and wind direction. I trust that is fine.

Regards,
AOAW

Hi @Andre.White,

Yes, that is correct.

The inputs StdScale1, StdScale2, StdScale3, Standard Deviation, and Length Scale in the user-defined profile input file are only used for the with TurbModel = USRVKM.

To plot the spectrum of the wind velocity or the correlation coefficient of the spatial coherence, you’d have to extract the time series from the wind data file and post-process these data.

Best regards,

Hi @Jason.Jonkman:
Noted.
For the spectrum, what I would like to know is if there is a setting in TurbSim to create the output time series in a form that I can use the data to plot the spectrum and correlation coefficient. Similar to .out files in OpenFAST?

Thank you.

Regards,
AOAW

Hi @Andre.White,

TurbSim has an option to output in human-readable format by setting WrFMTFF = TRUE; however, the file sizes will be large for a finely discretized grid.

NREL has also provided a MATLAB-based script for reading the binary-formatted files output by TurbSim, i.e., read_BTS.m: matlab-toolbox/readfile_BTS.m at main · OpenFAST/matlab-toolbox · GitHub.

Best regards,

Noted. Thank you @Jason.Jonkman .

Regards,
AOAW

Hi @Jason.Jonkman:
I was able to output some hub height turbulence parameters from TurbSim. However I would like some clarification on what some of the variables are. See part of output below.
I know that u’, w’ and v’ are the turbulent components of the wind where u’ should be the horizontal component of the turbulent wind which is used to determine the turbulence intensity.
1) Can you please say what are U, Uh, Ut, V and W? It looks like Uh is the mean horizontal wind speed at Hub Height and others are other components of this wind speed.
2) Also can you please confirm that the units are all m/s?
Finally, I have used the pwelch method to generate the wind power spectrum; loglog(frequency, spectrum).
3) Can you please clarify if I am to take square root of u’,v’,w’ to get the wind spectrum?

Thank you.

Regards,
AOAW

Dear @Andre.White,

Here are my answers:

  1. U, V, and W are the individual components of the velocity vector along X, Y, and Z, respectively. Uh is the horizontal (2D) vector magnitude of this velocity and Ut is the total (3D) vector magnitude of this velocity.
  2. Yes, all velocities are in m/s. The Reynolds stresses and TKE are in m^2/s^2.
  3. No, there is no square root needed in the computation of a spectrum.

Best regards,

@Jason.Jonkman thank you.

Regards,
AOAW

Hi @Jason.Jonkman I am actually trying to model the FOWT in hurricane conditions. I have therefore increased the reference wind speed to a value that it could be in the hurricane eyewall. I have read a paper by Kapoor et al (2020) where they used a value of 88.4 m/s as the reference wind speed. They had modelled a fixed based OWT. When I use 88.4 m/s as reference wind speed (by way of reminder this is for parked/idle turbine) and increase the blade structural damping, I still get the following error:
FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
HydroDyn_CalcOutput:HDOut_MapOutputs: Angles in GetSmllRotAngs() are larger than 0.4 radians. ED_HD_InputOutputSolve:HydroDyn_CalcOutput: Angles in GetSmllRotAngs() are larger than 0.4 radians.
HydroDyn_CalcOutput:HDOut_MapOutputs: Angles in GetSmllRotAngs() are larger than 0.4 radians. Time: 230 of 3600 seconds. Estimated final completion at 16:33:45.
FAST_Solution:FAST_AdvanceStates:SolveOption2c_Inp2AD_SrvD:InflowWind_CalcOutput:CalcOutput:IfW_FF Wind_CalcOutput [position=(36.246, -213.36, 128.89) in wind-file coordinates]: FF wind array boundaries violated: Grid too small in Y direction. Y=-213.36; Y boundaries = [-200, 200]
OpenFAST encountered an error at simulation time 236.1 of 3600 seconds. Simulation error level: FATAL ERROR

It there anything else you think I can do to get the model to stabilize? I have even turned off the flapwise and edgewise DOF of the blades but this does not solve the problem. Please let me know as modelling for hurricane conditions is a significant part of what I am studying.

Thank you.

Regards,
AOAW

Dear @Andre.White,

Just a couple comments:

  • You are getting this error far into the simulation. What does the response look like up until this error? What doe the time series of blade and tower deflection and platform displacement look like?

  • It could very well be that the FOWT you are simulating (IEA 15-MW RWT atop the UMaine semi) is not designed for such extreme conditions.

Best regards,

Hi @Jason.Jonkman thank you.
I did not think about the second point that you have raised. That could possibly be the case.
With regard to the first questions, I have another question:
How would what the responses look like help me to decipher the error? Just trying to understand here.

Thank you.

Regards,
AOAW

Dear @Andre.White,

If the model was physically or numerically unstable, I would expect the solution to blow up much more quickly (as you were seeing before). Given that the model now generates an error far into the simulation, I’m curious if there are signs of an instability at that point (so if an instability is isolate to some combination of events), or if the deflections are already large throughout and it just so happens that the error is triggered at some point due to unfortunate combination of effects. But mostly, it is very difficult to respond to questions such as you pose without more information.

Best regards,

1 Like

Thanks @Jason.Jonkman. Noted. I will look at the problem some more.

Regards,
AOAW

Hi @Jason.Jonkman:
I am getting an error in TurbSim that I have never got before.
It occurs when I change the Grid height to 280 m and above. Even when I use 279.5 m it works fine. This is the error:
Running TurbSim (v2.00.07a-bjj, 14-Jun-2016).
Reading the input file “150m_88mps_wind_shearJCS1r.inp”.
Calculating the spectral and transfer function matrices:
** u-component matrices (IEC coherence method)**
** v-component matrices (identity coherence)**
** w-component matrices (identity coherence)**
** Generating time series for all points:**
** u-component**
** v-component**
** w-component**
** Computing hub-height statistics**
forrtl: severe (157): Program Exception - access violation
Image PC Routine Line Source
ntdll.dll 00007FFC539D5BB6 Unknown Unknown Unknown
ntdll.dll 00007FFC539D47B1 Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D9A480C0 Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D9A480FA Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D8EC2679 Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D8EC11A9 Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D951D2E6 Unknown Unknown Unknown
TurbSim_x64.exe 00007FF7D9A47E9C Unknown Unknown Unknown
KERNEL32.DLL 00007FFC538C7034 Unknown Unknown Unknown
ntdll.dll 00007FFC53A02651 Unknown Unknown Unknown
These are some of the input parameters that I used in TurbSim:

--------Turbine/Model Specifications-----------------------
31 NumGrid_Z - Vertical grid-point matrix dimension
31 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
3650 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
3650 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds unless UsableTime is “ALL”)
150 HubHt - Hub height [m] (should be > 0.5GridHeight)
280.0 GridHeight - Grid height [m]
750 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”,“IECVKM”,“GP_LLJ”,“NWTCUP”,“SMOOTH”,“WF_UPW”,“WF_07D”,“WF_14D”,“TIDAL”,“API”,“USRINP”,“TIMESR”, or “NONE”)
“unused” UserFile - Name of the file that contains inputs for user-defined spectra or time series inputs (used only for “USRINP” and “TIMESR” models)
“1-ED3” IECstandard - Number of IEC 61400-x standard (x=1,2, or 3 with optional 61400-1 edition number (i.e. “1-Ed2”) )
7.38 IECturbc - IEC turbulence characteristic (“A”, “B”, “C” or the turbulence intensity in percent) (“KHTEST” option with NWTCUP model, 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]
“USR” WindProfileType - Velocity profile type (“LOG”;“PL”=power law;“JET”;“H2L”=Log law for TIDAL model;“API”;“USR”;“TS”;“IEC”=PL on rotor disk, LOG elsewhere; or “default”)
“windshear.dat” ProfileFile - Name of the file that contains input profiles for WindProfileType=“USR” and/or TurbModel=“USRVKM” [-]
150 RefHt - Height of the reference velocity (URef) [m]
88.4 URef - Mean (total) velocity at the reference height [m/s] (or “default” for JET velocity profile) [must be 1-hr mean for API model; otherwise is the mean over AnalysisTime seconds]
“default” ZJetMax - Jet height [m] (used only for JET velocity 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------------
“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 for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
“default” InCDec2 - v-component coherence parameters for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
“default” InCDec3 - w-component coherence parameters for general or IEC models [-, m^-1] (e.g. “10.0 0.3e-3” in quotes) (or “default”)
0.85 CohExp - Coherence exponent for general model [-] (or “default”)

--------Coherent Turbulence Scaling Parameters-------------------
“/home/lkilcher/work/nwtc/turbsim/trunk/Test/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 DistScl - Disturbance scale [-] (ratio of event dataset height to rotor disk). (Ignored when Randomize = true.)
0.5 CTLy - Fractional location of tower centerline from right [-] (looking downwind) to left side of the dataset. (Ignored when Randomize = true.)
0.5 CTLz - Fractional location of hub height from the bottom of the dataset. [-] (Ignored when Randomize = true.)
30 CTStartTime - Minimum start time for coherent structures in RootName.cts [seconds]

I have entered my own wind shear profile. Please let me know if you know what could have caused this error and how I could fix it. Ideally I would like to enter a GridHeight of 295 m.
Thank you.

Regards,
AOAW

Dear @Andre.White,

Can you also share your windshear.dat user-defined wind profile file?

Best regards,

Hi @Jason.Jonkman:
See data below.

Height Wind Speed Wind Direction Standard Deviation Length Scale
“(m) (m/s) (deg, cntr-clockwise ) (m/s) (m)”

10.0 72.0 0
20.0 76.0 0
30.0 79.5 0
40.0 82.5 0
50.0 84.0 0
60.0 85.0 0
70.0 86.0 0
80.0 87.0 0
90.0 87.2 0
100.0 87.8 0
110.0 88.2 0
119.0 89.4 0
120.0 89.7 0
130.0 89.9 0
140.0 90.0 0
150.0 90.1 0
160.0 90.2 0
170.0 90.3 0
180.0 90.4 0
190.0 90.5 0
200.0 90.6 0
210.0 90.7 0
220.0 90.8 0
230.0 90.9 0
240.0 91.0 0
250.0 91.1 0
260.0 91.2 0
275.0 91.25 0

Regards,
AOAW

@Jason.Jonkman that is the height, wind speed and wind direction respectively. Where wind direction/veer is 0 degrees.

Regards,
AOAW