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10.2 Design evaluation ALTERNATIVE BLADE DESIGN From appendix J it is seen that profile A exhibits the best aerodynamic properties. These are repeated on figure 10.1, which shows the lift coefficient Cl, the drag coefficient Cd and the glide ratio GR of profile A. The error bars of figure 10.1 show the standard deviation of three independent tests. This is further elaborated in appendix J. Figure 10.2: Lift coefficient Cl, drag coefficient Cd and glide ratio GR of profile A The glide ratio is approximately 10% of the NACA 4412 glide ratio, which indicates a significantly lower aerodynamic performance. The airfoil data is employed in the rotor design tool by the method described in Appendix D. On basis of this, a three-bladed rotor is designed to have the same power output as the NACA-based rotor at a wind speed of 12 m/s. U<strong>sin</strong>g a tip-speed ratio � of 4 and a fixed blade pitch � of 6�, the resulting blade radius is 2.05 m and the rotor efficiency is 40% (Cp = 0.24). This should be compared to the 1.35 m blade radius of the current design that has an efficiency of 93% (Cp = 0.55). Full details of the rotor tool calculation are provided as att. 5. The more than 50% increase in blade length results in considerably higher loads on each blade. Whether it is possible for the blade to structurally withstand the loads, depends on the material used. It is considered unlikely that a section-cut plastic drain pipe of the given length is strong and stiff enough, but a steel plate or a reinforced pipe section might suffice. Further development of the airfoil and structural verification of the blades that are based on it is left to a future project, as described in chapter 12. 93
ALTERNATIVE BLADE DESIGN 94 10.3 Summary The option of u<strong>sin</strong>g simple airfoils for the blade design was investigated, as it potentially makes it possible to produce blades by even simpler means than with the current design. Two different designs based on curved plates were subjected to wind tunnel tests and the best candidate was selected. The test and subsequent analysis of the results showed that to achieve the same power output with the simple airfoil as with the current, the blade length would have to be increased from 1.35 m to 2.05 m. The possibility of creating a blade of this length with sufficient structural strength was recommended to be investigated in a future project.
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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
Page 49 and 50: ROTOR 42 6.1 Number of blades Moder
Page 51 and 52: ROTOR 44 Figure 6.4: Blade design s
Page 53 and 54: ROTOR Table 6.3 provides a material
Page 55 and 56: ROTOR Figure 6.7 displays the lift
Page 57 and 58: ROTOR Figure 6.9: Rotor power outpu
Page 59 and 60: ROTOR 6.2.3 Manufacturing During th
Page 61 and 62: ROTOR 54 The three sides of the tem
Page 63 and 64: ROTOR When the carving process is f
Page 65 and 66: ROTOR 58 Figure 6.17: Blade attachm
Page 67 and 68: ROTOR 60 Figure 6.19: Rotor power o
Page 69 and 70: ROTOR 62 Figure 6.22: Efficiency
Page 71 and 72: ROTOR sidering the output from the
Page 73 and 74: ROTOR 66
Page 75 and 76: 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: ALTERNATIVE BLADE DESIGN 92 10.1 Ai
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 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
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LIST OF ATTACHMENTSAIRFOIL With the
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LIST OF ATTACHMENTSAIRFOIL Complete
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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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