2013 Vol. 34, No. 10

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Forewords of Special Issue : Progress in Large Wind Turbine Aerodynamics
2013, 34(10): 1-2.
Abstract(2292) PDF(1136)
Status of Large Scale Wind Turbine Technology Development Abroad
2013, 34(10): 1003-1011. doi: 10.3879/j.issn.1000-0887.2013.10.001
Abstract(1558) PDF(2196)
In order to facilitate the domestic large scale (multi-megawatt) wind turbine development in China, the efforts and achievements in the area abroad were reviewed and summarized. Not only the popular horizontal axis wind turbines on-land, but also offshore wind turbines, vertical axis wind turbines, high altitude wind turbines and shroud wind turbines were discussed. It is intended to provide a comprehensive comment and assessment about their basic working principle, economic aspects and environmental impacts.
Design and Wind-Tunnel Verification of Large-Size Wind Turbine Airfoils
HAN Zhong-hua, SONG Wen-ping, GAO Yong-wei
2013, 34(10): 1012-1027. doi: 10.3879/j.issn.1000-0887.2013.10.002
Abstract(1770) PDF(2263)
For a family of specially tailored airfoils, the shapes of sections along the span of the blades are the most important elements for design of wind turbine blades. The airfoils with excellent performance can dramatically improve the capability of capturing wind power, reducing structural weight to save cost of manufacturing and transportation, and lowering inertial loads as well as loads due to gust. First, the development of the main wind turbine airfoil families around the world since 1990’s was reviewed, such as S series, DU series, RIS series, and FFA series. Second, the progress of NPU-WA series for megawatt-size wind turbine was summarized, including the design process and wind-tunnel experiments. Model tests were carried out in NF-3 wind-tunnel’s two dimensional test section, which was the largest low-speed two dimensional test section in Asia with the Reynolds number up to 5 millions. The further improvement of NPU-WA airfoils for lower roughness sensitivity was also reviewed. Last, the outlook on developing new NPU-WA series for multi-megawatt wind turbines in the near future was presented.
Independent Research and Development (R & D) Progress in Large-Scale Wind Turbine Blades With Coordinated Aerodynamics, Structure and Loads
XU Yu, LIAO Cai-cai, RONG Xiao-min, WANG Qiang
2013, 34(10): 1028-1039. doi: 10.3879/j.issn.1000-0887.2013.10.003
Abstract(966) PDF(1342)
According to the three key elements in the blade design process, which were aero-design, structural design and loads prediction, independent R & D progress was summarized and analyzed. In aero-design, the computational fluid aerodynamic (CFD) method, vortex method and the blade element momentum method (BEM) were described. Then based on the BEM method, which was widely used in the engineering design, solutions for designing blades applied in low-speed wind area were pointed out. In structural design, a brief overview of the traditional design and analysis methods based on beam model was given. Then, the defects of these methods when used in thin-shell structures of large-scale composite blade were analyzed. At last, the application progress in the finite element method (FEM) used in the blade structure analysis was also described. In loads prediction, the effects of the loads prediction on blades and the entire wind turbine were introduced. The progress in load forecasting was also described. Then, a through analyzing the relationship between these three key elements, a conclusion, that developing a blade optimization design system with coordinated aerodynamics, structure and loads could truly meet the requirements of high efficiency and low cost, was got. At last, the main directions need further study are pointed out. Those are, high efficiency and low uploaded airfoils, structural nonlinear finite element analysis, aero-structure coupling research and enacting design standard etc. The aim is establishing a blade R & D system suitable for the conditions of wind resources in China, and promoting the development of wind power in the country.
Application of Bamboo-Based Laminates in the Design of Large-Scale Wind Turbine Blades
WANG Long, LI Hui, WANG Tong-guang
2013, 34(10): 1040-1047. doi: 10.3879/j.issn.1000-0887.2013.10.004
Abstract(1070) PDF(1136)
From the viewpoint of material and structure in the design of large-scale wind turbine bamboo-based blades, a series of mechanical property tests and basic characteristics of bamboo-based laminates as the major enhancement materials for blade spars were briefly introduced. Based on these material performance data, the aerodynamic and structural design of a 1.5 MW wind turbine bamboo-based blade in conventional form was carried out. Then, the process of the blade structure-overlay was documented in some detail especially. For completeness, some technical issues existing in the design of bamboo-based blade were discussed.
Progresses in Application of Computational Fluid Dynamics to Large Scale Wind Turbine Aerodynamics
ZHANG Zhen-yu, ZHAO Ning, ZHONG Wei, WANG Long, XU Bo-feng
2013, 34(10): 1048-1058. doi: 10.3879/j.issn.1000-0887.2013.10.005
Abstract(1550) PDF(1412)
The applications of computational fluid dynamics (CFD) methods in aerodynamic problems for the design of large scale wind turbines were introduced, especially progresses in the aerodynamic analyses of wind turbine profiles, numerical simulation of flow around wind turbines, numerical computation of aerodynamic performance and multi-objective aerodynamic optimization for large scale wind turbine blades were extensively discussed. With CFD methods, significant prediction was conducted for the 2D/3D aerodynamic characteristics of wind turbine airfoils and blades, the vortex structure of the wake flow was accurately captured. Combined with the efficient multi-objective genetic algorithm, a 1.5 MW NH1500 optimum blade design with high wind energy conversion efficiency was obtained.
The Progress in Wind Turbine Wind Tunnel Test Technology and Research Works
XIAO Jing-ping, CHEN Li, WU Jie, DUAN Xue-feng
2013, 34(10): 1059-1072. doi: 10.3879/j.issn.1000-0887.2013.10.006
Abstract(1507) PDF(1434)
Based on the backgroud of UAE phase VI and MEXICO preoject as well as related research works in CARDC, the recent progress in wind turbine measurement technologies such as flow field and pressure distribution and aerodynamic load measurement technology was summarized. Some important research results have also been introduced, such as results of wind tunnel effct, determination of equivalent far-field free coming flow conditions for bladeelement, 3D rotation effect, dynamic inflow effect, the flow field structure and the induced effects, etc. the wind tunnel experimental research works and some ideas on large wind turbine of CARDC were also simply introduced.
Investigation of Three-Dimensional Effect on Blades of a Wind Turbine Based on Field Experiments
LI De-shun, LI Ren-nian, WANG Xiu-yong, WEI Lie-jiang, LI Yin-ran, QIANG Yan, LIU Zhi-qiang
2013, 34(10): 1073-1082. doi: 10.3879/j.issn.1000-0887.2013.10.007
Abstract(1325) PDF(1187)
Field experiments were performed on a 33 kW horizontal axis wind turbine. The curves of pressure distribution were gathered by 191 pressure sensors disposed span-ward on 7 particular sections of a blade. Then, the 3D numerical simulation of the wind turbine and 2D numerical simulation of the 7 airfoils were performed in comparison with the field experiment results, and the lift and drag coefficients of the 7 airfoils were also obtained for 3D and 2D. The investigation was performed for the turbine aerodynamic characteristics under the 3D effects. At last, conclusions were drawn. The pressure difference of the airfoils first increases and then decreases from the blade tip to the blade root, and the curves of the pressure distribution show the characteristics of flow separation on the blade obviously. The 3D results of pressure on the 7 airfoils are more consistent with the experiments than 2D. There is a more violent 3D flow on the blade surface, especially at the blade tip and the blade root.
Research Status and Trend of Wind Turbine Aerodynamic Noise
LI Xiao-dong, XU Ying-bo, JIANG Min
2013, 34(10): 1083-1090. doi: 10.3879/j.issn.1000-0887.2013.10.008
Abstract(1211) PDF(1333)
The main components of wind turbine aerodynamic noise were introduced firstly. Then a detailed review was addressed about the theoretical prediction, experimental measurement and numerical simulation methods of wind turbine noise, with specific attention to the application aspect. Furthermore, suppression techniques for wind turbine aerodynamic noise were discussed. And the perspective of future research on wind turbine aerodynamic noise was presented finally.
Aeroelastic Analysis of Large Horizontal Axis-Wind Turbine Blades
TANG Di, LU Zhi-liang, GUO Tong-qing
2013, 34(10): 1091-1097. doi: 10.3879/j.issn.1000-0887.2013.10.009
Abstract(1432) PDF(2029)
A nonlinear aeroelastic analysis method for large horizontal axis wind turbines was presented. A vortex wake method and a nonlinear finite element method were coupled to realize the approach. The vortex wake method was used to predict the wind turbine aerodynamic loads and the rotor model was built with 3D shell elements. The averaged aerodynamic forces along the azimuth angle were applied to the structure model and the nonlinear static aeroelasticity was computed. The wind rotor modalities were obtained in the static aeroelastic configuration through linearization of the coupled equations. The static aeroelasticity and dynamic aeroelasticity were calculated for the NH 1500 wind turbine. Results show that the structural geometrical nonlinearities will significantly reduce the displacements and vibration amplitudes of the wind turbine blades. The structural geometrical nonlinearities are non-negligible for both the static aeroelasticity and dynamic aeroelasticity.
Recent Progress in Wave-Current Loads on Foundation Structure with Piles and Cap
LIU Hua, WANG Ben-long, XUE Lei-ping, HE Yan-ping
2013, 34(10): 1098-1109. doi: 10.3879/j.issn.1000-0887.2013.10.010
Abstract(1243) PDF(1235)
The foundation structure with piles and cap is one of the widely used structures for offshore wind farm construction in shallow water. The experimental studies on hydrodynamic loads acting on the piles and cap under irregular waves and currents were summarized with discussion about the pile group effect on wave forces and wave impact loads upon the cap locating near the free surface. Through theoretical solution of the wave diffracted by the cap and application of the Morison equation to evaluate the wave force on piles, the effects of the cap on wave force upon piles were investigated. Based on the RANS equations and the VOF method, a numerical wave basin was developed to simulate the wavestructure interaction. The computed maximum wave force on the foundation structure with piles and cap agreed well with the measured data. The violent deformation, breaking and runup of wave around the structure were provided and discussed. Further work on the turbulent flow structures and large deformation of the free surface due to interaction of waves and foundation structures of offshore wind farms is needed to develop efficient approaches for evaluating hydrodynamic loads under the waves and currents.
Offshore Floating Wind Turbines and Related Dynamic Problems
ZHU Ren-chuan, MIAO Guo-ping, FAN Ju, LIU Hua
2013, 34(10): 1110-1118. doi: 10.3879/j.issn.1000-0887.2013.10.011
Abstract(1463) PDF(2491)
As one kind of green energy, ocean wind power is plentiful in deep sea, and more and more offshore wind power plants are being on to be constructed in the sea water of depths over one hundred meters. While the offshore floating wind turbine system was working, the wind turbine, floating foundation and mooring system will affect each other through coupling with wind, wave and current actions. The various offshore floating wind turbine systems and the corresponding environmental loads were briefly discussed. It was be a difficult key problem for the future to conduct comprehensive analysis of aerodynamic-hydrodynamic-service system-structure for the coupling effects of the offshore floating wind turbine system and make full consideration of environmental flow field and dimension characteristics of the system structure, there for exploration and sythesis of suitable theories and approaches should be done in advance.