Wind Turbine Airfoils and Blades Optimization Design Theory

Price: $67.00


Author: Jin Chen
Language: English
ISBN/ISSN: 9787030548535
Published on: 2018-01

1 Introduction
1.1 Introduction
As a kind of clean and renewable energy, wind energy is inexhaustible and is attracting increasing attention from all over the world. Of the global wind energy reserves, 2 × 107 MW are available from the whole 2.74 × 109 MW, which is 10 times more than can be extracted from exploitable water resources. Wind energy is abundant in China, with the energy on land amounting to 2.53 × 105 MW.
With innovations in wind turbine theories, the application of new materials andthe development of manufacturing technologies, wind power technology is continuouslyimproving, with unit capacity increasing from the 10-kilowatt scale to themulti-megawatt (MW) scale. The average unit capacity of wind turbines has increasedto twenty times that of twenty years ago. Before 2008, large-scale wind turbine manufacturingproduced only few products. German Repower manufactured the first 5 MWprototype in 2004. German Enercon has recently developed the second generationof 6 MW direct-drive wind turbines whose diameter is increased to 127 m from 112 m(4.5 MW). In recent years, more and more companies have started to design and developlarge-scale wind turbines. Danish Vestas is developing the 4 MW-Micon offshorewind turbine. Spanish Gamesa has developed a 4.5–5 MW model. German BARD hasdeveloped a 5 MW wind turbine series and three have been installed on land andoffshore. In 2009, BARD announced that it would start developing 6.5 MW wind turbines.Siemens has completed testing a 3.6 MW direct-drive conception wind turbine.Dutch Darwind is developing a 5 MW direct-drive wind turbine. American Clipper isgoing to cooperate with Britain to develop 7.5 MW and 10 MW units. AMSC, which iscooperating with the US Department of Energy, plans to manufacture a 10 MW unitwith superconducting generators. So the large-scale wind turbine is becoming themainstream of future market development and applications. Meanwhile, prompted bythe large-scale developments in international wind industries, Chinese wind energycompanies have also become involved in the fierce competition among large-scale windturbines. In 2009, China made a breakthrough in research and manufacturing MW-scalewind turbines. For example, a 3 MW wind power unit developed by Shenyang IndustrialUniversity has been successfully manufactured. 2.5 MW and 3 MW wind turbine unitsdeveloped by Goldwind have been put into trial operation in a wind farm [2, 3]. The6 MW offshore wind turbine unit developed by Sinovel in 2011 has been successfullymanufactured. And the 6 MW offshore wind turbine developed by National Power hasalso finished development and tests. In addition, Goldwind, DEC, Haizhuang, XEMCand so others are developing or have developed wind turbines whose capacity exceeds5 MW, indicating that research and manufacturing of large-scale wind turbines in Chinahas stepped into a new era.
Although the development of the global wind industry has, to some extent, been affected by the global economic crisis in recent years, newly installed capacity is still on the increase. According to statistics from the Global Wind Energy Council (GWEC), after the slower rate of increase of wind power in 2010, in 2011 the newly installed capacity globally amounted to 40 564 MW, which represented annual growth of more than 20 % [2]. Compared with capacity installed in 2010 of 18.94 GW, the annual capacity installed in China decreased in 2011 by 6.9 % to 17.63 GW. After rapid growth, the Chinese wind power market is entering a period of steady development. By the end of 2011, the Chinese wind market, with 45 894 wind turbines installed annually and capacity of 62.36 GW, continues to be the largest worldwide. The capacity installed annually in China since 2001 is shown in Fig. 1.1.
Fig. 1.1: Development of wind power in China.
During the years 2005–2010, many companies from abroad with great strength sought potential partners in China. For example, American GE and Danish Vestas have set up factories or cooperated with Chinese enterprises. Although Chinese enterprises have achieved initial successes. improved technologies and produced many wind power products, the core technologies of wind power are almost all controlled by large international companies. The blade is one of the most crucial parts of a wind turbine and its value amounts to 20 % of that of the whole wind turbine. Good design, reliable quality and superior performance are the decisive factors to ensure normal and stable operation of wind turbines.
1.2 The research in China and worldwide
The design theories for wind turbine airfoils and aerodynamic blade shapes are the decisive factors in wind turbine power performance and aerodynamic load characteristics. Structural design of composite blades is the crucial factor affecting stiffness characteristics of blades. Blade aeroelastic complex multidisciplinary coupling and collaborative method are used to investigate the aerodynamic performan 

Preface v
1 Introduction 1
1.1 Introduction 1
1.2 The research in China and worldwide 3
1.2.1 Research on wind turbine airfoils 3
1.2.2 Research on aerodynamic shape and performance of wind turbine blades 4
1.2.3 Research on structural design of composite wind turbine blades 5
1.2.4 Research on aeroelastic performance of wind turbine blades 6
2 Aerodynamic characteristics of wind turbine airfoils 9
2.1 Introduction 9
2.2 Basic theory of wind turbine airfoils 9
2.2.1 Geometric parameters of airfoils 9
2.2.2 Reynolds number 10
2.2.3 Mach number 11
2.2.4 Boundary layer 12
2.2.5 Potential flow solving method for an arbitrary airfoil 15
2.3 Aerodynamic characteristic of airfoils 18
2.3.1 Pressure coefficient of the airfoil 18
2.3.2 Lift coefficient 19
2.3.3 Drag coefficient 20
2.3.4 Pitching moment coefficient 21
2.4 Stall on airfoils 22
2.5 Roughness properties of airfoils 23
2.6 Influence of geometric parameters on aerodynamic characteristics 25
2.6.1 Influence of the leading edge radius of an airfoil 25
2.6.2 Influence of the maximum relative thickness and its position 25
2.6.3 Influence of the maximum camber and its position 26
2.7 Influence of Reynolds number on aerodynamic characteristics 26
2.8 Method of predicting aerodynamic performance of airfoils 26
2.8.1 Introduction to XFOIL and RFOIL 27
2.8.2 Airfoil aerodynamic performance calculation cases 27
2.9 Chapter conclusions 30
3 Integrated expressions of wind turbine airfoils 31
3.1 Introduction 31
3.2 Transformation theory of airfoils 31
3.2.1 Conformal transformation 31
3.2.2 Joukowsky transformation of airfoils 33
3.2.3 Theodorsen method 34
3.3 Integrated expression of airfoil profiles 36
3.3.1 The trigonometric series representation of airfoil shape function 37
3.3.2 The Taylor series representation of airfoil shape function 37
3.4 Airfoil profile analysis using integrated expressions 39
3.4.1 Type I airfoil profile 39
3.4.2 Type II airfoil profile 40
3.4.3 Type III airfoil profile 40
3.5 Versatility properties for integrated expression of airfoils 41
3.5.1 First-order fitting 42
3.5.2 Second-order fitting 45
3.5.3 Third-order fitting 45
3.6 Control equation of shape function 47
3.6.1 Characteristics of airfoil sharp trailing edge 47
3.6.2 Horizontal offset characteristics 47
3.6.3 Vertical offset characteristics 48
3.6.4 Design space 48
3.7 Convergence analysis of integrated expression of airfoils 49
3.7.1 Convergence characteristic of airfoil shape 50
3.7.2 Convergence characteristic of airfoil aerodynamic performance 54
3.8 Chapter conclusions 56
4 Theory of parametric optimization for wind turbine airfoils 57
4.1 Introduction 57
4.2 Design requirements of wind turbine airfoils 58
4.2.1 Structural and geometric compatibility 59
4.2.2 Insensitivity of the maximum lift coefficient to leading edge roughness 59
4.2.3 Design lift coefficient 59
4.2.4 The maximum lift coefficient and deep stall characteristics 60
4.2.5 Low noise 60
4.3 Single object optimization of wind turbine airfoils 60
4.3.1 Objective function 60
4.3.2 Design variables 61
4.3.3 Design constraints 61
4.3.4 Optimization method with MATLAB 62
4.3.5 Optimized results 62
4.3.6 Roughness sensitivity of the optimized airfoils 64
4.3.7 Comparative analysis of the performance of optimized airfoils 69
4.4 Multiobjective optimization of the wind turbine airfoils 72
4.4.1 Design variables 72
4.4.2 Objective function 74
4.4.3 Design constraints 76
4.4.4 Multiobjective genetic algorithm 77
4.4.5 WT series wind turbine airfoils of high performance 78
4.4.6 WTH series wind turbine airfoils with high lift-to-drag ratio 87
4.4.7 WTI series wind turbine airfoils with low roughness sensitivities 89
4.5 Design of airfoils with medium relative thickness 91
4.5.1 Geometric characteristics analysis of medium thickness airfoils 91
4.5.2 Aerodynamic characteristics of airfoils with medium thickness 93
4.5.3 The design of a new airfoil with medium thickness 94
4.5.4 The effects of turbulence, Reynolds number and blade rotation 97
4.6 Design of airfoils based on noise 100
4.6.1 Acoustic theory for wind turbines 100
4.6.2 The measurement of noise 101
4.6.3 The acoustics model of the airfoil 103
4.6.4 Comparison of noise calculations 113
4.6.5 Influence of geometric parameters of airfoils on noise 115
4.6.6 Design of wind turbine airfoils with high efficiency and low noise 118
4.7 Airfoil design based on a 2D power coefficient 123
4.7.1 The optimization model 125
4.7.2 The optimization flow chart 127
4.7.3 CQU-DTU-B airfoil series 128
4.7.4 Influence of airfoil trailing edge on the performance of the airfoil 138
4.8 Improved design of airfoils using smooth curvature technique 140
4.8.1 Smooth continuity of 

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