Using TurbSym for the 15 MW IEA Wind Turbine

Wind & Water Inflow Turbulence
1

Hi everyone!

I am running simulations for the 15 MW IEA with Turbsym. I am starting with a turbulent windtype with the following specifications:

--------Turbine/Model Specifications-----------------------
67 NumGrid_Z - Vertical grid-point matrix dimension
65 NumGrid_Y - Horizontal grid-point matrix dimension
0.05 TimeStep - Time step [seconds]
630 AnalysisTime - Length of analysis time series [seconds] (program will add time if necessary: AnalysisTime = MAX(AnalysisTime, UsableTime+GridWidth/MeanHHWS) )
60 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)
260 GridHeight - Grid height [m]
250 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”)
“UsrSpec.inp” 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”) )
“B” 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]
“PL” 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”)
“unused” 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]
3 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)
0,14 PLExp - Power law exponent [-] (or “default”)
“default” Z0 - Surface roughness length [m] (or “default”)

I have followed the suggestions from the user guide for these parameters. I do not know why, at the time of the simulation with turbsym, the following code in cmd appears for unlimited time:

Running TurbSim (v2.00.07a-bjj, 14-Jun-2016).

Reading the input file “TurbSim_UsrSpec3ms_turb.inp”.
Calculating the spectral and transfer function matrices:
u-component matrices (IEC coherence method)

The v-component matrices and w-component matrices should appear also, but it takes so much time for it to appear (after one hour waiting,it does not appear).
As I said, I have been one hour waiting for it to be run, but still i do not receive the .bts file… Is this because the num_gridZ and num_gridY are large?? If so, is there any chance of making the simulation run in short time?

Thank you

2

Dear @Alberto.Utrera,

It appears to me that you are setting NumGrid_Z and NumGrid_Y too large, which would make TurbSim take a long time to process. We typically recommend using a TurbSim spatial discretization equal to the max chord length of the blade, which from the IEA Wind 15-MW reference wind turbine is around 6 m. So, with GridHeight of 260 m, you should be able to drop NumGrid_Z to 44 and with a GridWidth of 250 m, you should be able to drop NumGrid_Y to 42.

Best regards,

3

Thank you very much @Jason.Jonkman.

I was wondering also a couple of things:

1º About the 15 MW IEA hub mass, which one is the correct? I am saying this because in the excel called “IEA-15-240-RWT_tabular” in the Documentation section it says that the hub mass is 21,41 ton. In the Table 5-1 of the Definition of the IEA Wind 15-Megawatt Offshore Reference Wind Turbine
Technical Report, it says that it is 190 ton. Additionally, the Elastodyn input file for the 15 MW IEA claims that the hub mass is 69,36 ton. Which one is correct? This not only happens with hub mass, but with other parameters(Nacelle mass, tower mass, …). I suppose it is important to fix just only one hub mass, otherwise, people might take different hub masses.

2º Is it good to start the simulation with a Tstart that avoids the first transitory response? I am saying this because i want to design a graph TowerTopDisplacement-WindVelocity. I suppose it is good to take only the average of the permanent response, right? Or is it good to take the transitory response as well?

3ºApart from using the linearization, how could i get the following natural frequencies:
-flapwise blade natural frequency
-edgewise blade natural frequency
-flapwise tower natural frequency
-edgewise tower natural frequency
I suppose i have to use the formula sqrt(k/m), but i do not know how exaclty to use it

Many thanks

4

Dear @Alberto.Utrera,

Regarding (1), I’ll let someone more knowledgeable about the the IEA Wind 15-MW reference wind turbine answer.

Regading (2), TStart is useful to avoid seeing the initial start-up transient in the OpenFAST output, e.g. when running load cases to compute ultimate and fatigue loads. I’m not sure why type of graph you are considering, but it kind of sounds like you want the steady-state response.

Regarding (3), linearization followed by Eigenanalysis is the most most straightforward way to obtain the full-system natural frequencies, which is effectively computing SQRT(K/M) for the generalized mass and stiffness matrices of the full system. You can also identify natural frequencies through post-processing of the time-domain response or by applying system identification techniques, but it is not so easy with these approaches to figure out which frequency corresponds to which mode. For the IEA Wind 15-MW reference turbine, some of the natural frequencies are also documented in its specifications report: https://www.nrel.gov/docs/fy20osti/75698.pdf.

Best regards,

5

On the hub mass and other nacelle properties, there is an entry on the IEA Wind 15-MW repo FAQ that the original table in the report had a number of issues that have been corrected. The tabular data Excel file (“Hub_System” entry) and the Elastodyn file are consistent. Same is true with the nacelle properties (Elastodyn uses the “Above_yaw” line item in the Excel file).

6

Hi Alberto Utrera,
Could you please tell me how we can use 15 MW IEA Wind Turbine? For example I am using 5 MW wind turbine.

7

Dear @JMRaisulIslam.Shohag,

OpenFAST models of the IEA Wind 15-MW reference wind turbine–for both a fixed-bottom monopile and floating VolturnUS semisubmersible–are available from the Task 37 repository: GitHub - IEAWindTask37/IEA-15-240-RWT: 15MW reference wind turbine repository developed in conjunction with IEA Wind.

Best regards,

8

HI @JMRaisulIslam.Shohag , What do you mean by How we can use?
I suppose you refer how to run simulations with different wind speeds (both in steady windtype and turbulent)?