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BASIS FOR CALCULATIONS Figure A.1: Rayleigh probability density function for wind speed with an average of 6 m/s. The graph indicates the probability of the occurrence of a specific wind speed The wind distribution is important as it indicates the frequency of occurrence of the indi- vidual load conditions. It is also used for calculating the annual energy production, see section 6.3.1. The wind conditions are subdivided into normal and extreme conditions. The normal conditions generally concern long-term structural loading and operating conditions that occur frequently during normal operation, while the extreme conditions represent the rare, but potentially critical external design conditions that are defined as having a 50 year recur- rence period [5, p. 69]. The conditions are used in the load cases, described in appendix A.3. It should be noted that the defined external conditions are not intended to cover wind conditions experienced in tropical storms such as hurricanes, cyclones and typhoons. A.2 Other environmental conditions Like the wind conditions, the other external conditions for the wind turbine can be subdivided into normal and extreme external conditions. The environmental properties of each condition are listed below [5, p. 59]. These are used in design calculations where applica- ble. 121
LIST OF ATTACHMENTSBASIS FOR CALCULATIONS Normal condition 122 � Normal system operation ambient temperature range of –10 °C to +40 °C � Relative humidity of up to 95 % � Solar radiation intensity of 1000 W/m 2 � Air density of 1.225 kg/m 3 Extreme condition � Extreme temperature range of –20 °C to +50 °C Other extreme environmental conditions include lightning, ice loading and earthquakes. IEC 61400-2 contains no minimum requirements for these conditions when u<strong>sin</strong>g standard SWT classes and these are therefore not taken into account in the present project. A.3 Load cases Actual wind turbine load conditions are quite complicated, as the loads are variable and as the structure itself moves in ways that affect the loading. Very detailed mathematical models must be used to fully analyse these interacting load effects. As mentioned in section A.1 the present wind turbine configuration however makes it possible to use simplified and conservative load models that provide insight into the response of the wind turbines to steady and cyclic loads. Several load cases have been established in accordance with IEC 61400-2 to verify the structural integrity of the key components: blades, shaft and tower, respectively. These take into consideration all relevant load cases with a reasonable probability of occurrence within the categories: � Turbine operation without fault and with normal external conditions � Turbine operation without fault and with extreme external conditions � Turbine operation with fault and extreme external conditions � Turbine installation with normal external conditions The simplified load model of IEC 61400-2 take into account stochastic variations in the wind speed (wind turbulence), as well as sudden and brief increases of the wind speed over its mean value (gusts). This is done conservatively by defining the wind inflow conditions for each load case. The design load cases are tabulated in table A.2. For each load case the appropriate type of analysis is stated. F refers to analysis of fatigue loads, to be used in the assessment of fatigue strength. U refers to the analysis of ultimate loads such as analysis of exceeding the maximum material strength.
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WIND TURBINE DESIGN
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ABSTRACT At the request of the Engi
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CONTENTS 1 Introduction ...........
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E Structural analysis of blades ...
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INTRODUCTION members. Today EWB-DK
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INTRODUCTION Figure 1.2: Left pictu
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INTRODUCTION 6
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PROBLEM STATEMENT reconfigured with
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PROBLEM STATEMENT 10
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METHODOLOGY Figure 3.1: Flow chart
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METHODOLOGY 14 3.1 Calculation meth
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CONCEPTUALISATION the kinetic wind
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CONCEPTUALISATION Figure 4.3: (a) D
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CONCEPTUALISATION issues due to tur
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CONCEPTUALISATION 22 Figure 4.8: Ty
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CONCEPTUALISATION � Darrieus 24 F
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CONCEPTUALISATION 26 Figure 4.13: G
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CONCEPTUALISATION Figure 4.14: Powe
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CONCEPTUALISATION 30 ID Requirement
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CONCEPTUALISATION most suitable sol
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CONCEPTUALISATION The embodiment de
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DESIGN PRESENTATION The main dimens
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DESIGN PRESENTATION The design prop
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DESIGN PRESENTATION The background
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ROTOR 42 6.1 Number of blades Moder
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ROTOR 44 Figure 6.4: Blade design s
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ROTOR Table 6.3 provides a material
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ROTOR Figure 6.7 displays the lift
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ROTOR Figure 6.9: Rotor power outpu
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ROTOR 6.2.3 Manufacturing During th
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ROTOR 54 The three sides of the tem
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ROTOR When the carving process is f
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ROTOR 58 Figure 6.17: Blade attachm
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ROTOR 60 Figure 6.19: Rotor power o
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ROTOR 62 Figure 6.22: Efficiency
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ROTOR sidering the output from the
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ROTOR 66
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GENERATOR AND ELECTRICAL SYSTEM 68
Page 77 and 78: GENERATOR AND ELECTRICAL SYSTEM The
Page 79 and 80: GENERATOR AND ELECTRICAL SYSTEM Fig
Page 81 and 82: GENERATOR AND ELECTRICAL SYSTEM 74
Page 83 and 84: YAW AND FURLING For an upwind wind
Page 85 and 86: YAW AND FURLING (16), which are bol
Page 87 and 88: YAW AND FURLING 80 8.2 Furling syst
Page 89 and 90: YAW AND FURLING 82 8.3 Summary The
Page 91 and 92: TOWER Concrete tower 84 Figure 9.1:
Page 93 and 94: TOWER 86 Figure 9.4: Turbulent air
Page 95 and 96: TOWER Figure 9.7 shows the tower ba
Page 97 and 98: TOWER models [41, p. 111]. Under ce
Page 99 and 100: ALTERNATIVE BLADE DESIGN 92 10.1 Ai
Page 101 and 102: ALTERNATIVE BLADE DESIGN 94 10.3 Su
Page 103 and 104: DESIGN EVALUATION 96 6 W Low-cost m
Page 105 and 106: DESIGN EVALUATION Weaknesses 1) The
Page 107 and 108: FURTHER DEVELOPMENT � Foundation
Page 109 and 110: FURTHER DEVELOPMENT 102
Page 111 and 112: CONCLUSION proposal is highly flexi
Page 113 and 114: NOMENCLATURE Abbreviation Descripti
Page 115 and 116: NOMENCLATURE Lgs Distance between u
Page 117 and 118: NOMENCLATURE 110
Page 119 and 120: BIBLIOGRAPHY [14] Magenn Power Inc.
Page 121 and 122: BIBLIOGRAPHY [53] H. J. Larsen, H.
Page 123 and 124: LIST OF ATTACHMENTSBASIS FOR CALCUL
Page 127: LIST OF ATTACHMENTSBASIS FOR CALCUL
Page 139 and 140: LIST OF ATTACHMENTSROTOR THEORY Thi
Page 141 and 142: LIST OF ATTACHMENTSROTOR THEORY 134
Page 143 and 144: LIST OF ATTACHMENTSROTOR THEORY Cho
Page 145 and 146: LIST OF ATTACHMENTSROTOR THEORY 138
Page 147 and 148: LIST OF ATTACHMENTSROTOR DESIGN TOO
Page 149 and 150: LIST OF ATTACHMENTSROTOR DESIGN TOO
Page 151 and 152: LIST OF ATTACHMENTSAIRFOIL With the
Page 153 and 154: LIST OF ATTACHMENTSAIRFOIL Complete
Page 155 and 156: LIST OF ATTACHMENTSSTRUCTURAL ANALY
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LIST OF ATTACHMENTSSTRUCTURAL ANALY
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LIST OF ATTACHMENTSBLADE ATTACHMENT
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LIST OF ATTACHMENTSSTRUCTURAL VERIF
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LIST OF ATTACHMENTSTOWER ANALYSIS T
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LIST OF ATTACHMENTSFURLING AND YAW
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LIST OF ATTACHMENTSALTERNATIVE AIRF
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LIST OF ATTACHMENTSCOMPLIANCE WITH
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