100kW风力发电机叶片疲劳分析

结合有限元分析方法和叶片振动试验方法,利用最少的试验设备,检测出叶片危险部位的相应数据,以提高疲劳试验的可靠性。通过理论计算和数学建模相结合的方法,确定叶片阴阳两面最大变形位置,使试验条件更符合叶片的实际工况。分析试验结果显示,被测叶片达到了设计标准的要求。     

大型风力发电机旋转叶片结构动力特性分析

大型风力发电机叶片的结构动力特性是叶片结构设计时考虑的重要方面,其固有自振频率对于整个风力机的安全运行具有重要意义。文章基于现代柔性多体动力学理论和有限元数值分析相结合的方法,对5MW风力发电机叶片的固有振动特性进行分析。结合复合材料叶片结构特性及结构参数,建立了5 MW风机复合材料叶片有限元模型,计算了考虑动力刚化及阻尼效应影响下的固有频率和振型,揭示了动力刚化效应对叶片固有频率的影响规律;并结合坎贝尔图,对叶片进行了共振分析,为叶片的结构设计及优化提供了参考依据。     

风力发电机复合材料叶片结构特性分析

随着对风力发电机叶片性能要求的提高,新型复合材料在风力发电机叶片制造中的应用得到了广泛的关注与研究。由于新型复合材料及风力发电机叶片结构具有一定的复杂性,因此风力发电机复合材料叶片的结构特性很难计算。文章基于FAST软件,以1.5 MW风力发电机复合材料叶片为例,运用有限元原理将叶片分成若干叶素面,通过描述各个截面的几何形状、内部结构以及材料等来建立叶片模型,对风力发电机复合材料叶片的结构特性进行了分析研究。     

风力发电机叶片振动方程及固有频率

分析了风力发电机转子叶片所受的外力和外力矩，给出了叶片俯仰振动、扭转振动和摆动振动方程及相应的一阶振动固有频率。     

生物质风力发电机叶片复合材料制造因素的研究

通过研究生物质风力发电机叶片复合材料制造过程中的几个关键问题,找出生产生物质风力发电机叶片复合材料的最佳工艺,为进一步的生产打下基础.     

风力发电机叶片翼型气动性能分析与数值模拟

使用ANSYS FLUENT软件对风力发电机叶片翼型DU-93-W-210和S809的空气动力性能进行定常数值模拟和仿真分析,并和实验数据进行对比与分析。鉴于阻力系数的数值模拟结果与实验数据相比误差较大,通过分析其原因,发现在攻角较小时,翼型表面上有相当一部分流动属于层流流动,若对整个计算域使用湍流模型,显然会增大阻力系数。在此基础上,对CFD模型进行修改,在FLUENT模型里设置翼型转折点前为层流区域,从而能精确预测小攻角时的阻力系数。     

基于重量模型的风力发电机叶片设计问题的研究

以空气动力学、结构动力学和机械工程学为理论基础,分析了影响叶片重量的主要设计因素.在考虑风电机组叶片设计因素的前提下,利用机理分析法建立了风力发电机组叶片的重量模型.通过实际机型的数据验证了模型的合理性,说明利用重量模型研究风电机组设计的方法是可行的.     

潮流能水轮机复合材料叶片结构力学性能分析及选型

叶片是潮流能水轮发电机的主要承载构件,直接影响着整机的性能和寿命。文章针对100 k W水平轴潮流能水轮发电机复合材料叶片,结合叶片受力特点,提出了腹板式和箱梁式两种全复合材料叶片结构,并应用有限元软件ANSYS建立了含有复合材料铺层信息的三维模型,分析了叶片的强度、叶尖挠度及材料失效性。通过对两种叶片结构对比分析表明,箱型梁式叶片的结构形式更为合理,叶片自重可减少21%。文章的研究成果可为今后同类叶片的设计提供参考。     

Effects of composite fiber orientation on wind turbine blade buckling resistance

This paper utilized the inherent directional properties of composite materials to increase the critical buckling load of a 70 m carbon/glass hybrid wind turbine blade. The effect of changing the fiber orientations of the less stiff, off‐axis glass fiber plies (referred to as stability plies in this paper) was studied via nonlinear finite element buckling simulations. The orientation of the stability plies was found to influence the onset of the Brazier effect, which further influenced blade stability and buckling failure location. Although both blade weight and laminate thickness remained constant, an increase in critical buckling load of 8% was achieved with a negligible change in bending stiffness. The more stable blade allowed for removal of material leading to a decrease in maximum laminate thickness and a drop in blade mass of 3.3%. Modifications to the ply stacking sequence and carbon fiber usage were also considered and were found to affect the buckling load but not necessarily the optimum fiber orientation of the stability plies. Copyright © 2013 John Wiley & Sons, Ltd.     

大型水平轴式风电叶片的结构设计

风电叶片是风力发电设备的关键部件之一,其制造成本占总成本的20%～30%.叶片结构是叶片捕获风能的保证,并直接影响风力发电设备的运行寿命.因此,叶片结构设计的好坏在很大程度上决定了风力发电设备的可靠性和利用风能的成本.文章从材料、结构形式、铺层设计、结构分析等4个方面详细地阐述了风电叶片结构的设计技术.     

Numerical validation of a finite element thin‐walled beam model of a composite wind turbine blade

This paper presents a numerical validation of a thin‐walled beam (TWB) finite element (FE) model of a realistic wind turbine rotor blade. Based on the theory originally developed by Librescu et al. and later extended to suit FE modelling by Phuong, Lee and others, this computationally efficient yet accurate numerical model is capable of capturing most of the features found in large blades including thin‐walled hollow cross section with variable thickness along the section's contour, inner reinforcements, arbitrary material layup and non‐linear anisotropic fibre‐reinforced composites; the present application is, for the time being, restricted to linearity. This one‐dimensional (1D) FE model allows retaining information of different regions of the blade's shell and therefore approximates the behaviour of more complex three‐dimensional (3D) shell or solid FE models more accurately than typical 1D FE beam models. A 9.2 m rotor blade, previously reported in specialized literature, was chosen as a case study to validate the static and dynamic behaviour predicted by a TWB model against an industry‐standard 3D shell model built in a commercial software tool. Given the geometric and material complexities involved, an excellent agreement was found for static deformation curves, as well as a good prediction of the lowest frequency modes in terms of resonance frequencies, mode shapes and frequency response functions; the highest (sixth) frequency mode shows only a fair agreement as expected for an FE model. It is concluded that despite its simplicity, a TWB FE model is sufficiently accurate to serve as a design tool for the recursive analyses required during design and optimization stages of wind turbines using only readily available computational tools. Copyright © 2011 John Wiley & Sons, Ltd.     

TMT40.3大型风力机叶片气动性能分析

基于BLADED软件平台,对TMT40.3大型风力机叶片的气动性能进行了分析.分析结果表明:TMT40.3大型风力机叶片应用在GL3A风场时的额定功率能达到1 650 kW,所承受的疲劳强度和极限载荷均能满足该款风力机叶片的设计要求,在叶尖速比为7.8～11.4的风能利用系数均在0.46以上,最高可达0.486,具有较好的气动性能和较宽的风速适应范围.     

Influence of a wind turbine service life on the mechanical properties of the material and the blade

This paper presents results out of investigations of the DEBRA‐25 wind turbine blades. Almost unique in the history of modern wind energy, these blades were in operation for 18 years next to a weather station and were investigated afterward. Therefore, the loads experienced in the operational life could be post‐processed accurately with the measured data of the weather station and the turbine. The blades are made of materials that are similar with today's wind turbines. Furthermore, intensive laboratory tests and free field tests have been carried out, and all load assumptions and data and results are still available today. The results include experimental investigations on the moisture content of the load‐carrying material, static and fatigue behavior of the material, the relaxation of the coupling joints, the natural frequencies of the blade and a full scale static blade test. It is shown that the structural performance of the DEBRA‐25 service blades is comparable with modern wind turbine blades. Although some damage was found by visual inspection, the service blade of the DEBRA‐25 showed excellent mechanical behavior in the full scale blade test. Only small changes of the edgewise eigenfrequencies were detected. The pre‐tensioning forces of the IKEA bolts, where the two blade parts are connected, were measured and were still adequate. Copyright © 2012 John Wiley & Sons, Ltd.     

Revisiting the structural collapse of a 52.3 m composite wind turbine blade in a full‐scale bending test

Full‐scale structural tests enable an in‐depth understanding of how composite blades respond to specific applied loads. Blade strength can be validated, and necessary modifications can be made to improve structural performance and/or reduce blade weight. This study revisits the structural collapse of a 52.3 m composite blade with new research content. Specifically, the present work examines the chain of events captured in the video record of the blade collapse and provides direct phenomenological evidence of how the blade collapsed in its ultimate limit state. In addition, three‐dimensional strains are investigated by reconstructing the root transition region of the blade using solid brick elements in a finite element analysis. The strain components responsible for particular failure characteristics are identified. The structural response of the blade is investigated numerically. Interactive failure phenomena associated with strains, local buckling and material failure are examined in detail. The study shows that local buckling of the sandwich panels with unbalanced construction drives progressive failure of the composite materials and eventually leads to blade collapse owing to significant failure of the load‐carrying spar cap. Design modifications of the blade are proposed and validated with the test of a new blade. With respect to the latest DNV GL standard, this study notes a possible method to predict delamination and skin/core debonding failures. This study also recommends the use of three‐dimensional solid elements in finite element analysis, especially when the strength and failure of large blades are of concern. Copyright © 2017 John Wiley & Sons, Ltd.     

Development of fatigue life prediction method and effect of 10-minute mean wind speed distribution on fatigue life of small wind turbine composite blade

This study aims to develop a fatigue life prediction method and to identify the effect that a 10-minute mean wind speed distribution has on the fatigue life of a small-scale wind turbine composite blade. First, combining the von Karman isotropic turbulence model and the Weibull distribution for a 10-minute mean wind speed provided us with the 1-Hz full wind history for a specific time period. Accordingly, the fatigue stress spectra at the blade's fatigue-critical locations (FCLs) were created by applying a stress tensor, in which the interaction between flapwise and edgewise bending moments was taken into consideration. The fatigue life of a composite blade can be predicted with a reliability R = 95% by applying the P–S–N curve obtained from the constant amplitude fatigue tests and rainflow cycle counting, and cumulative damage rule to the fatigue stress spectra. To acquire the second-order regression equation, nonlinear regression analysis was performed on the fatigue lives, which were simulated by using the proposed fatigue life prediction method. In this equation, the variables were the shape parameter, K, and the scale parameter, C, of the Weibull distribution for a 10-minute mean wind speed. The effects of the Weibull parameters on fatigue life were evaluated through the sensitivity analysis of the equations.     

风电叶片后缘疲劳加载设备摇臂支架结构优化设计

基于模态叠加理论对风电叶片后缘疲劳加载设备摇臂支架进行模态分析和拓扑结构优化。文章通过对风电叶片后缘疲劳加载模型进行合理简化,对摇臂支架所受载荷进行了等效分析,建立了摇臂支架的有限元模型,进而基于模态叠加法对摇臂支架进行动力学响应分析,得到了各阶次的频率分布情况。最后,以各板件厚度为约束条件,建立以质量最轻为目标函数的数学模型,结合OptiStruct软件得到了优化结果。结果表明,优化后的摇臂支架质量减少了985 kg,且在相同工况下,摇臂支架的变形量减少了4.7 mm,验证了优化后摇臂支架结构的可行性,为后缘加载装备的工程应用提供了理论支撑。     

Evaluation of equivalent structural properties of NREL phase VI wind turbine blade

This paper presents the structural model development and verification process for the National Renewable Energy Laboratory (NREL) Phase VI wind which consists of the blades, rotor, nacelle, and tower. The mass and stiffness properties of all parts had to be clearly defined to develop the structural model for the entire turbine. However, it was difficult to define the geometries and material properties of the blade structure and power generating machinery because of their complexity. To perform a FSI analysis, fluid and structural models that shared the associated interface topology had to be provided. With the help of an eigen-value analysis, the structural stiffness and mass properties were verified in comparison with the values reported by NREL. A finite element (FE) model that included the blade, nacelle, and tower was developed based on the NREL's reported data. The commercial FE software ANSYS was used to develop the geometry and mesh, and to perform the eigen-value analysis. The various material properties and configurations of the entire turbine system were tested to obtain the proper material properties to determine this value. Overall, the proposed geometry, material, and mass properties were in good agreement with the measurements, but need to be discussed further.