TurbSim User's Guide: Version 1.06.00 - NREL

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UsableTime: Usable Time Series Length [s]This parameter is the usable length (in seconds) of the data to output. This number differsslightly from the actual amount of data that TurbSim outputs. Because AeroDyn requires thatthere be data both upwind and downwind of the tower in case the turbine is yawed, it mandatesthat there be extra data in the FF files to shift the data enough to ensure that the turbine residesentirely within the wind-data domain. TurbSim always adds the amount of time equal to the gridwidth divided by the mean HH wind speed, u , to the requested amount of usable time:hubGridWidthOutputTime = UsableTime + . (4)uThe analysis time must be at least as large as the output time:AnalysisTimehub≥ OutputTime . (5)If necessary, TurbSim increases AnalysisTime to satisfy this relationship.HubHt: Turbine Hub Height [m]The HubHt parameter is hub height of the turbine for which the inflow is being generated.TurbSim uses the metric system so enter the value in meters. This parameter is used as areference height for determining the grid location.GridHeight: Height of the Grid [m]This parameter is the distance (in meters) between the top and bottom of the grid. The top of thegrid is assumed to be aligned with the top of the rotor disk (see Figure 5), and because all pointsof the grid must be above ground level, 1 GridHeight < HubHt .2When choosing a value for GridHeight, keep in mind that AeroDyn does not allow any part ofthe blade—including all system displacements—to lie outside the FF grid. The grid height mustbe large enough to encompass the entire rotor disk of FF files. See the parameter GridWidth forfurther discussion.GridWidth: Width of the Grid [m]This parameter is the width of the grid in meters. The rotor is assumed to be centeredHeight = Width Height > Width Height < WidthFigure 5. Example grid and rotor placements: the circles pictured here are the rotor diametersassumed by TurbSim; the actual rotor diameter(s) will be smaller than pictured10
horizontally on the grid. If you are generatingFF files for AeroDyn, the grid width—like theheight—must be large enough to ensure that nopart of the blade lies outside the grid, even whenthe system is displaced.TurbSim assumes that the diameter of the rotordisk is the smaller of the GridHeight andGridWidth values. Because AeroDyn mustinterpolate within the grid for any point at whichit needs wind speeds (i.e., AeroDyn cannotextrapolate), GridHeight and GridWidth shouldbe larger than the rotor diameter. In fact,AeroDyn warns users if the grid width andheight are not at least 10% larger than the rotordiameter. For turbines that move a lot duringsimulation (e.g., floating wind turbines), the gridmight have to be even larger.(a)(b)As pictured in Figure 5, the hub is in thehorizontal center of the grid, and the turbine hubheight plus assumed rotor radius determines thetop of the grid.VFlowAng: Mean Vertical Flow Angle [°]This parameter is the mean vertical angle of thewind, which is constant across the entire grid.Enter the angle in degrees, and do not exceed45° in magnitude. A positive value means thatthe wind is blowing uphill; a negative valueindicates that the wind is blowing downhill. SeeHFlowAng and Figure 6 for more details.(c)HFlowAng: Mean Horizontal FlowAngle [°]This parameter is the mean horizontal(crosswise) angle of the wind in degrees. In allcases except the GP_LLJ model, the horizontalflow angle is constant across the entire grid. Forthe GP_LLJ model, which introduces directionshear with height, HFlowAng is the horizontalangle at hub height.The mean flow angles VFlowAng andHFlowAng are used to rotate the wind from itsalignment with the mean flow to the inertialreference frame. Users should be cautious,11Figure 6. Example of TurbSim grids asimplemented in AeroDyn: (a) The inertial framecoordinate systems and planes “marching”along positive X, regardless of flow angles, (b)wind field with both flow angles 0°, (c) the samewind field with VFlowAng = 8° andHFlowAng = 15°
Page 4 and 5: AcknowledgementsTurbSim was written
Page 6 and 7: Table of ContentsAcknowledgements .
Page 8 and 9: List of FiguresFigure 1. TurbSim si
Page 10 and 11: Figure G-6. Unstable velocity spect
Page 12 and 13: Buhl added the ability to generate
Page 14 and 15: “CertTest.bat” and set the envi
Page 16 and 17: TurbSim assumes that parameters are
Page 18 and 19: parameter RICH_NO) is greater than
Page 22 and 23: however, because AeroDyn—in its i
Page 24 and 25: Figure 8. Coherent turbulent kineti
Page 26 and 27: Figure 9. Default jet wind speed fo
Page 28 and 29: ⎛1000⎞θ = T ⎜ ⎟⎝ p ⎠0.
Page 30 and 31: The three α variables are coeffici
Page 32 and 33: IncDec2: Spatial Coherence for the
Page 34 and 35: Table 8. Valid CTEventFile EntriesI
Page 36 and 37: files a “.bin” extension. At ea
Page 38 and 39: generated for the FF Bladed-style
Page 40 and 41: Spectral ModelsTurbSim uses a modif
Page 42 and 43: K( )S f = UStar2s1, K⎛ z ⎞⎛φ
Page 44 and 45: NWTCUP: The NREL National Wind Tech
Page 46 and 47: Figure 20. GPLLJ-model stable/neutr
Page 48 and 49: (NumPeaks K = 2, K = u, v, w) and e
Page 50 and 51: Cohi,j( f )iiSij( f )( ) ( )= , (49
Page 52 and 53: where u( z ) is the mean wind speed
Page 54 and 55: atmosphere. To obtain more events w
Page 56 and 57: See Appendix H in this document for
Page 58 and 59: • The statistics calculated in th
Page 60 and 61: References[1] Laino, D. J.; Hansen,
Page 62 and 63: [28] Olesen, H.R.; Larsen, S.E.; H
Page 64 and 65: Appendix B: TurbSim Quick-Start Gui
Page 66 and 67: Appendix C: Flow ChartsTurbSim Inpu
Page 68 and 69: TurbSim InputFileTurbine/Model Spec
Page 70 and 71:
TurbSim InputFileMeteorologicalBoun
Page 72 and 73:
TurbSim Input FileDefault Input Val
Page 74 and 75:
Appendix D: Full-Field TurbSim Bina
Page 76 and 77:
Appendix E: Full-Field Bladed-Style
Page 78 and 79:
Appendix F: Tower Data Binary File
Page 80 and 81:
Appendix G: Velocity Spectra Compar
Page 82 and 83:
Default UStar (m/s)SMOOTH 0.644NWTC
Page 84 and 85:
Default UStar (m/s)SMOOTH 0.656NWTC
Page 86 and 87:
Appendix H: Sample AeroDyn Coherent
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