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。     

Damage mechanics based design methodology for tidal current turbine composite blades

A material model based on the Puck phenomenological failure criteria for fibre and inter-fibre failure of glass-fibre and carbon-fibre reinforced polymer composites is presented. The model is applied through a user-defined material subroutine for 3D shell elements. Sub-modelling is used for detailed analysis of the highest stressed regions in the blades. The material model is incorporated into a methodology for the design and analysis of composite tidal current turbine blades. The methodology employs an iterative design process with respect to a number of failure criteria to ensure optimal structural and material performance of the blade. The methodology is automated using the Python programming language to enable efficient variation of model parameters for various design conditions. The forces acting on the blades are determined from blade element momentum theory for a number of turbine operating conditions. The results of a design case study for a typical horizontal axis device are presented to demonstrate the methodology.     

Classical flutter analysis of composite wind turbine blades including compressibility

For wind turbine blades with the increased slenderness ratio, flutter instability may occur at lower wind and rotational speeds. For long blades, at the flutter condition, relative velocities at blade sections away from the hub center are usually in the subsonic compressible range. In this study, for the first time for composite wind turbine blades, a frequency domain classical flutter analysis methodology has been presented including the compressibility effect only for the outboard blade sections, which are in the compressible flow regime exceeding Mach 0.3. Flutter analyses have been performed for the baseline blade designed for the 5‐MW wind turbine of NREL. Beam‐blade model has been generated by making analogy with the structural model of the prewisted rotating thin‐walled beam (TWB) and variational asymptotic beam section (VABS) method has been utilized for the calculation of the sectional properties of the blade. To investigate the compressibility effect on the flutter characteristics of the blade, frequency and time domain aeroelastic analyses have been conducted by utilizing unsteady aerodynamics via incompressible and compressible indicial functions. This study shows that with use of compressible indicial functions, the effect of compressibility can be taken into account effectively in the frequency domain aeroelastic stability analysis of long blades whose outboard sections are inevitably in the compressible flow regime at the onset of flutter.     

风力机复合材料叶片内部结构典型铺层及分析

叶片为风力发电装置中最核心、最关键的部件之一,其材料的选择对于叶片设计至关重要.大型风力机叶片普遍采用复合材料.将叶片视为一个变截面悬臂梁,基于经典层合板理论和梁帽式铺层方法,利用美国可再生能源国家实验室(NREL)发布的叶片结构分析软件PreComp和BModes计算叶片截面刚度、固有频率以及极限载荷作用下的变形.将计算值和ANSYS软件的分析结果进行比较,结果表明梁帽式铺层方法合理可行,且不影响叶片性能,在实际工程应用中有较大的使用价值.     

叶片材料及根部结构对潮流能水轮机性能的影响

转轮叶片材料及根部结构对潮流能水轮机水力性能和结构性能有较大影响。文章基于CFD方法对转轮直径为2 m,3种叶片根部方案的潮流能水轮机在不同来流速度工况下的水力性能进行了稳态数值模拟,计算结果表明,当来流速度为4 m/s,采用根部方案2时,机组达到最高效率73.39%。在此基础上,利用单向流固耦合的方法计算分析了该根部方案下采用4种不同材料转轮叶片的结构性能,分析结果表明,叶片采用结构钢、碳纤维HexMC和碳纤维RTP-1389时,最大应力均为130 MPa,未超过许可应力强度,结构钢最大总形变为6.55 mm,玻璃纤维最大总形变为104.72 mm。     

浅谈当前兆瓦级风力机叶片

世界风电机组技术发展的趋势是兆瓦级大功率,作为兆瓦级风力机核心部件的叶片是如何制造的?又有些什么特性呢?其发展趋势是什么?等等,本文就此做一概括介绍,供读者参考.     

考虑翘曲效应的风力机叶片弯扭耦合特性计算方法

为了研究截面翘曲对大型风力机叶片弯扭耦合特性的影响,分别建立考虑翘曲效应和不考虑翘曲效应的梁模型,并对叶根截面、翼型截面特性进行了计算,表明考虑翘曲效应的梁模型在计算叶片截面刚度时得到的结果更准确。采用考虑翘曲效应的方法计算了5 MW风力机叶片的截面刚度,分析了叶片梁帽铺层角度对风力机叶片弯扭耦合特性的影响。结果表明,无论是否考虑翘曲效应,获得最大弯扭耦合特性的梁帽铺层角度都为20°;在同样的梁帽铺层角度下,翘曲效应对叶片不同部位(特别是在翼型过渡区域及气动翼型区域)的弯扭耦合系数影响很大。     

Design and performance of a double-pitch wind turbine with non-twisted blades

A new design has been proposed for inexpensive wind turbine blades with high power coefficients.The new wind turbine blade has been subdivided into two, each with a different pitch angle, to optimise aerodynamic flow, absence of twist, and carries a variable chord along the blade itself.The new blade reveals some energy loss due to the tip vortices of each blade part (which can be minimised by winglets), yet proves that it is possible to create a wind turbine with high power coefficients.To design and evaluate the performance of the new wind turbine a numerical code, developed by the authors and based on blade element momentum theory, was implemented after validation by experimental measurement found in scientific literature. The code led to better choices of layout to maximise turbine performance.     

Shape optimization of wind turbine blades

This paper presents a design tool for optimizing wind turbine blades. The design model is based on an aerodynamic/aero‐elastic code that includes the structural dynamics of the blades and the Blade Element Momentum (BEM) theory. To model the main aero‐elastic behaviour of a real wind turbine, the code employs 11 basic degrees of freedom corresponding to 11 elastic structural equations. In the BEM theory, a refined tip loss correction model is used. The objective of the optimization model is to minimize the cost of energy which is calculated from the annual energy production and the cost of the rotor. The design variables used in the current study are the blade shape parameters, including chord, twist and relative thickness. To validate the implementation of the aerodynamic/aero‐elastic model, the computed aerodynamic results are compared to experimental data for the experimental rotor used in the European Commision‐sponsored project Model Experiments in Controlled Conditions, (MEXICO) and the computed aero‐elastic results are examined against the FLEX code for flow past the Tjæreborg 2 MW rotor. To illustrate the optimization technique, three wind turbine rotors of different sizes (the MEXICO 25 kW experimental rotor, the Tjæreborg 2 MW rotor and the NREL 5 MW virtual rotor) are applied. The results show that the optimization model can reduce the cost of energy of the original rotors, especially for the investigated 2 MW and 5 MW rotors. Copyright © 2009 John Wiley & Sons, Ltd.     

风电叶片静力加载控制系统设计及验证

风电叶片静力加载过程中各个加载节点之间存在加载力耦合,导致加载不同步。因此,对多节点静力加载控制系统进行了深入研究。控制方案采用PC-主控制器-从控制器-检测装置的网络构架模式,通过Delphi进行数据采集及现场监控;为使5个加载节点同步加载,增强系统的抗干扰性,首次将动态矩阵控制(DMC)应用于风电叶片静力加载过程,达到较为精确解耦的目的。最后,将设计的控制系统应用于Aeroblade62-6.0型风电叶片的静力试验,结果表明,该系统控制效果良好,可以满足静力加载试验的要求。     

复合材料与风力机叶片

叶片是风力发电设备的关键部件,随着风机容量的大型化,风机叶片也向轻量化、低成本和高性能化发展.阐述了风力机叶片技术的研发趋势,介绍了复合材料叶片设计、材料、制造、试验分析和验证等相关技术,给出了碳纤维在叶片上应用的现状、发展前景和有关叶片的新技术,提出了发展风机叶片技术的相关建议.     

舰用燃气涡轮叶片常见失效分析

针对舰用燃气轮机使用环境、运行状态及运行失效数据,全面分析了影响舰用燃气轮机涡轮叶片工作寿命的常见失效模式及其失效机理,为舰用燃气轮机涡轮叶片剩余寿命预测模型的建立提供了可靠的依据.     

风机叶片的发展概况和趋势

由于煤炭、石油等化石能源资源有限且存在严重环境污染的危险,人们自然将目光集中在那些污染少、可持续供应的新能源上,因此发展风电成为了解决全球环境与能源问题的重要手段。在1887～1888年的冬天,美国的Charles F.Brush建造了世界第一座全自动风力发电机并成功发电,     

潮流水轮机的研究进展

概述了潮流水轮机的国内外发展情况,对3种不同结构的潮流水轮机的类型和特点作了比较分析,介绍了潮流水轮机的研究方法以及性能研究,指出了潮流水轮机的未来发展方向。     

Reliability design method for steam turbine blades

Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliability design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical calculation of test data. The fatigue strength and the vibration design reliability of turbine blades are determined with the aid of a probabilistic design method and by interference models for stress distribution and strength distribution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades. __________ Translated from Chinese Journal of Applied Mechanics, 2007, 24(3): 331–335 [译自: 应用力学学报]     

变桨距风力机叶片的气动优化设计

首先利用Wilson方法进行叶片的外形初步设计,然后以设计攻角作为变量,以额定风速下功率系数最大为优化目标,建立了1 MW变桨距风力机叶片气动外形优化模型,采用遗传算法进行了优化再设计。通过对3叶片1 MW风力机进行的气动性能评价结果表明,优化后的风力机具有更好的气动性能,说明采用该优化方法进行变桨距风力机设计具有明显的优越性。     

On the structural topology of wind turbine blades

As wind turbines continue to grow in size, it becomes increasingly important to ensure that they are as structurally efficient as possible to ensure that wind energy can be a cost‐effective source of power generation. A way to achieve this is through weight reductions in the blades of the wind turbine. In this study, topology optimization is used to find alternative structural configurations for a 45 m blade from a 3 MW wind turbine. The result of the topology optimization is a layout that varies along the blade length, transitioning from a structure with trailing edge reinforcement to one with offset spar caps. Sizing optimization was then performed on a section with the trailing edge reinforcement and was shown to offer potential weight savings of 13.8% when compared with a more conventional design. These findings indicate that the conventional structural layout of a wind turbine blade is sub‐optimal under the static load conditions that were applied, suggesting an opportunity to reduce blade weight and cost. Copyright © 2012 John Wiley & Sons, Ltd.     

Lightning protection for wind turbine blades and bearings

The protection of wind turbines from lightning damage is increasingly important as they increase in size and are placed in locations where access to carry out repairs may be difficult. As blades are the most common attachment point of lightning, they must be adequately protected. In addition, the passage of lightning current through wind turbine bearings introduces a risk of lightning damage to these vital components. Investigations relating to the improvement of blade lightning protection systems have been carried out, including experiments designed to address the difficult problems involved in the protection of hydraulic cylinders used for tip brake control. Work has also focused on the ability of lightning current to cause damage to wind turbine bearings. The work has been a mixture of computer simulations and experimental testing using high‐voltage and high‐current facilities. Copyright © 2001 John Wiley & Sons, Ltd.     

Innovative design approaches for large wind turbine blades

A preliminary design study of an advanced 50 m blade for utility wind turbines is presented and discussed. The effort was part of the Department of Energy WindPACT Blade System Design Study with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the 1–10 MW size range. Two different blade designs are considered and compared in this article. The first is a fibreglass design, while the second design selectively incorporates carbon fibre in the main structural elements. The addition of carbon results in modest cost increases and provides significant benefits, particularly with respect to blade deflection. The structural efficiency of both designs was maximized by tailoring the thickness of the blade cross‐sections to simplify the construction of the internal members. Inboard the blades incorporate thick blunt trailing edge aerofoils (flatback aerofoils), while outboard more conventional sharp trailing edge high‐lift aerofoils are used. The outboard section chord lengths were adjusted to yield the least complex and costly internal blade structure. A significant portion of blade weight is related to the root buildup and metal hardware for typical root attachment designs. The results show that increasing the number of studs has a positive effect on total weight, because it reduces the required root laminate thickness. The aerodynamic performance of the blade aerofoils was predicted using computational techniques that properly simulate blunt trailing edge flows. The performance of the rotor was predicted assuming both clean and soiled blade surface conditions. The rotor is shown to provide excellent performance at a weight significantly lower than that of current rotors of this size. Copyright © 2004 John Wiley & Sons, Ltd.     

Electromagnetic energy harvester for monitoring wind turbine blades

The long composite blades on large wind turbines experience tremendous stresses while in operation. There is an interest in implementing structural health monitoring (SHM) systems inside wind turbine blades to alert maintenance teams of damage before serious component failure occurs. This paper proposes using an energy harvesting device inside the blade of a horizontal axis wind turbine to power a SHM system. The harvester is a linear induction energy harvester placed radially along the length of the blade. The rotation of the blade causes a magnet to slide along a tube as the blade axis changes relative to the direction of gravity. The magnet induces a voltage in a coil around the tube, and this voltage powers the SHM system. This paper begins by discussing motivation for this project. Next, a harvester model is developed, which encompasses the mechanics of the magnet, the interaction between the magnet and the coil, and the current in the electrical circuit. A free fall test verifies the electromechanical coupling model, and a rotating test examines the power output of a prototype harvester. Copyright © 2013 John Wiley & Sons, Ltd.