Dear Jason.Jonkman
Iâm tring to plot PSD of wind generated by Turbsim, and compare it with ideal IECKAI model. I extract wind-time series of hub high from .u file, use MATLAB function âperiodogramâ to calculate its PSD, here is my MATLAB script:
%% plot PSD of Turbsim wind
path1 = 'D:\FAST\OPENFAST\r-test-master-2.4\test\5MW_Baseline\Wind\90m_12mps_twr.u';
[v, y, z, dt, ny, nz] = loadFFtxt(path1);
y_cor = find(y==0);
z_cor = find(z==90);
v_hub = v(:,y_cor,z_cor);
Fs = 1/dt;
N = length(v_hub);
[psdestx,Fxx] = periodogram(v_hub,rectwin(N),N*10,Fs);
loglog(Fxx,pow2db(psdestx),'b');
hold on;
%% plot PSD of ideal IECKAI mode
v_hub = 15; %Mean wind speed of hub
Lk = 8.10*0.7*60;
sigma_k = 0.14*(0.75*v_hub+5.6);
f = (0.001:0.001:1);
s_k = 4*sigma_k^2*Lk/u_hub./(1+6.*f*Lk/u_hub).^(5/3); %Kaimal PSD from IEC61400-1
loglog(f, s_k, 'r');
xlabel('Frequency(Hz)');
ylabel('Sw(m²/s²)');
legend({'Ideal IECKAI';'Turbsim result'});
here is my Turbsim setting:
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; note that UsableTime has been decreased in this file so that the file distributed with the FAST CertTest isn't as large
---------Runtime Options-----------------------------------
13428 RandSeed1 - First random seed (-2147483648 to 2147483647)
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)
True 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)
False WrBLFF - Output full-field time-series data in BLADED/AeroDyn form? (Generates RootName.wnd)
True WrADTWR - Output tower time-series data? (Generates RootName.twr)
True 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)
False 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
0.05 TimeStep - Time step [seconds]
600 AnalysisTime - Length of analysis time series [seconds]
600 UsableTime - Usable length of output time series [seconds] (program will add GridWidth/MeanHHWS seconds) [bjj: was 630]
90.0 HubHt - Hub height [m] (should be > 0.5*GridHeight)
145.0 GridHeight - Grid height [m]
145.0 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") )
"B" 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]
PL WindProfileType - Wind profile type ("JET"=Low-level jet,"LOG"=Logarithmic,"PL"=Power law, or "default", or "USR"=User-defined)
80. RefHt - Height of the reference wind speed [m]
15 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------------
default Latitude - Site latitude [degrees] (or "default")
0 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-------------------
"M:\coh_events\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.
10.0 CTStartTime - Minimum start time for coherent structures in RootName.cts [seconds]
==================================================
NOTE: Do not add or remove any lines in this file!
==================================================
here is my Matlab result:
I have no idea about Why these two curves trending differently, could you give me some suggestions?
Best regards,
Jiantao
