wind energy resource evaluation in a site of central italy ... - WindSim

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4.6 RemarksThe terrain characteristics of the site and wind experimental data have beenpresented.The performed analysis allowed to highlight the dominant wind direction sectors,corresponding to 30 and 210 degrees, for the tower 5424, while 60 and 240 degrees,for the tower 5428.The tower 5424 has shown a different behavior of the flow between the twomeasurement station, respectively 15 and 30 meters, in the period November-December. This fact can be related to some kind of thermal seasonal effects whichcan influence the flow in a region very close to the ground. It must be noticed, in thiscase, the position of the tower 5424 in proximity of a cliff, which can induceorographic effects in the flow.According to the selected dominant sectors, a preview of the position of the windturbines for a plant layout proposal can be done by considering to put them in aseries of rows perpendicular to the main wind directions.The choice should be confirmed by the results of the simulations which will be carryout in chapter 5 and 6.73
CHAPTER 5. Test of the Free Stream Velocity (FSV)5.1 IntroductionThe purpose of this chapter is to find the right settings in order to describe thespeed vertical profile of the flow given as a boundary condition. Particularly, the freestream velocity of the geostrophic wind has been studied. In fact, the scalar value ofthe free stream velocity can be set in WindSim by the user in the Windfield module.The analysis of this input parameter has been done in three steps: first of all amesoscale model of the considered site has been created, keeping a coarse gridresolution; then, as a second step, a smaller microscale model with medium gridresolution has been studied, in order to put in evidence the recirculation effect ofthe flow; finally, another microscale model with fine grid resolution has been built,finding as a result the optimum value of the free stream velocity to set in WindSimfor further simulations.The microscale models have been studied using the “nesting technique”: thisprocedure consists in running a simulation of the windfield in the mesoscale modeland using this one to extract boundary conditions to be applied to the microscalemodels, which have to be created therefore in a zone inside the mesoscale site.5.2 Mesoscale ModelThe mesoscale model is presented in this section. The horizontal velocity field hasbeen calculated; using data of the tower 5428 at 50 meters height to scale theresults, the relative maps obtained with free stream velocities of 10 and 20 m/s arerespectively shown in Figure 5.1 and 5.2.It must be noticed that in proximity of the tower position the maps show a valueequal to 1, demonstrating that the scale procedure is correct.The maps have been extracted for 4 wind directions: 0, 90, 180, 270 degrees, at 30and 50 meters height.The test of the free stream velocity has been carried out for 4 scalar values: 1, 5, 10and 20 m/s.74
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UNIVERSITÀ DEGLI STUDI DI CAGLIARI
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IndexIndex page IAcknowledgmentsVII
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CHAPTER 4: Characteristics of the s
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6.7.1 Mean wind velocity page 1096.
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This thesis is the result of a prac
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WindSim is a software developed by
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CHAPTER 1. Atmospheric Boundary Lay
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Figure 1.1: Example of an atmospher
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1.5 The WindSim numerical codeWindS
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(κ−ε RNG or the Low Reynolds),
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1.5.4 RESULTSThe Results module all
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Figure 1.2: Example of TKE vertical
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CHAPTER 2. Simulations over flat te
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inlet position (0 meters), station
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2.4 Height distribution factor sens
Page 31 and 32: e decreased, to avoid to build thin
Page 33 and 34: Figure 2.10: Vertical profiles for
Page 35 and 36: CHAPTER 3. Simulations over 2D hill
Page 37 and 38: Table 3.1: Measurement coordinatesS
Page 39 and 40: The results shown above demonstrate
Page 41 and 42: Figure 3.6: Sketch of the 15 km lon
Page 43 and 44: Figure 3.9: Influence of the height
Page 45 and 46: Figure 3.13: Zoom of the hill top r
Page 47 and 48: 3.5.2) = ∙.The two models for att
Page 49 and 50: H [m] hill heightν[m 2 /s] air cin
Page 51 and 52: Figure 3.18: Particular of the nume
Page 53 and 54: Finally, the horizontal x velocity
Page 55 and 56: Figure 3.25: Z velocity componentFi
Page 57 and 58: 3.6 RemarksA CFD study of a boundar
Page 59 and 60: Some experimental wind data of this
Page 61 and 62: Both the pictures 4.3 and 4.4 have
Page 63 and 64: Table 4.2: Description of the color
Page 65 and 66: In this periods, data are recorded
Page 67 and 68: In the following pages, a short des
Page 69 and 70: 4.3.2 Mast 5424-15 m Period April-M
Page 71 and 72: 4.3.4 Mast 5424-15 m Period Novembe
Page 73 and 74: 4.3.6 Mast 5428-40 m Period April-M
Page 75 and 76: 4.3.8 Mast 5428-50 m Period Novembe
Page 77 and 78: 4.3.10 Mast 5428-30 m Period Novemb
Page 79 and 80: 4.4.2 Mast 542870
Page 81: 4.5.2 Mast 542872
Page 85 and 86: case the wind is blowing from the e
Page 87 and 88: Geometrical modelTable 5.3: Input p
Page 89 and 90: Figure 5.6: Vertical profiles in po
Page 91 and 92: The orthogonalization of the grid h
Page 93 and 94: Figure 5.9: Map of speed-ups for di
Page 95 and 96: Figure 5.30: Speed-2D at 30 m heigh
Page 97 and 98: Figure 5.12: Speed-2D at 30 m heigh
Page 99 and 100: CHAPTER 6. Analysis of the wind fie
Page 101 and 102: Table 6.2: Boundary conditions and
Page 103 and 104: 6.5 Vertical profiles of VelocityTo
Page 105 and 106: characterized by high wind speed (5
Page 107 and 108: From the error analysis, it is foun
Page 109 and 110: Anyhow, the trend of the linear int
Page 111 and 112: Concerning the CFD simulations, val
Page 113 and 114: Analyzing RMS error table for tower
Page 115 and 116: A general overview of the figure 6.
Page 117 and 118: 6.7 Cross Checking of wind dataIn t
Page 119 and 120: Figure 6.8 a/bFigure 6.8 c/dFigure
Page 121 and 122: Table 6.11: RMS error for cross che
Page 123 and 124: Figure 6.9 e/fFigure 6.9 g/hFigure
Page 125 and 126: Figure 6.10 g/hFigure 6.10 i/lFigur
Page 127 and 128: to have a better agreement during t
Page 129 and 130: Figure 7.2: Weibull fitting of the
Page 131 and 132: Figure 7.5: Perspective view of the
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The calculated AEP has been reporte
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ConclusionsIn this thesis the evalu
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Bibliography[1] CRASTO G. - Numeric
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