浮式海上风力机叶片气动性能的流固耦合分析

随着深水浮式海上风电场在世界范围内的兴起,浮式平台运动性能对风力机稳定运行及叶片气动载荷影响的研究具有重要意义。基于三维粘性不可压缩Navier-Stokes方程和适用于旋转流场分析的重整化群k-ε(RNG)湍流模型,数值模拟美国可再生能源实验室(NREL)5MW海上风力机的气动性能,并将数值模拟结果与NREL的设计参考数据进行对比分析,较好地验证了该数值模拟方法的有效性。进一步利用滑移网格技术模拟风力机叶片随浮式平台的典型周期性运动,实现浮式风力机叶片与周围流场的复杂非线性流固耦合分析,分别研究浮式平台不同运动幅值和运动周期对风力机叶片气动性能的影响规律,并从物理机理角度进行阐明分析。本文的主要研究成果,将对未来大型深水浮式海上风力机的气动性能分析及浮式平台系统的运动性能设计起到积极的指导作用。     

大型海上风力机尾迹区域风场分析

随着世界范围内海上风电场的不断兴起及海上风电场设计规模的日趋庞大,大型海上风力机尾迹区域风场特征的研究对于海上风电场的优化布局有着重要的指导意义。本文基于三维Navier-Stocks控制方程和适用于旋转流场分析的RNGk-ε湍流模型,采用滑移网格技术对美国可再生能源实验室(NREL)的5 MW海上风力机的性能及其尾迹区域的风场特征进行了较为系统的数值模拟。通过将不同风速下风力机输出功率的数值结果与NREL的设计参考数据进行对比,三维数值模型的有效性得到了很好地验证。此外,在此基础上进一步研究了大型海上风力机额定风速下及不同风轮转速下尾迹区域平均风速的分布特征,并得到了一系列具有参考价值的重要结论。     

海上浮式风力机支撑结构的流固耦合动力学研究

海上漂浮式风力机支撑结构动力载荷的确定不仅对于结构设计、施工过程非常重要,对于设施的运维保障同样重要。水动力载荷的计算可归为基于势流理论的理论模型和基于计算流体动力学的数值模型两类方法。本文简述了两类模型各自的基本原理,明确其优劣,为实际工程应用的合理建模提供参考。对于海洋工程,水池物理模型实验发挥着重要作用。本文以某结构型式的浮式支撑结构的物理模型实验为例,阐述了物理模型实验技术的局限性及改进措施,为工程建设提供必要的技术支撑。

     

风剪切对风力机叶片气动性能及尾迹形状的影响

风力机通常运行在非定常工况中,其气动性能及尾迹会随着工况的变化而变化.风剪切是风力机长期所处的环境,它会影响到叶片气动载荷、尾迹形状、总体性能等,分析风剪切作用下的叶片气动性能对风力机的设计有重要意义.本文采用一种时间步进自由涡尾迹(free vortex wake,FVW)方法,耦合FVW方法与风剪切模型,计算不同风...     

基于涡尾迹方法的风力机气动性能分析

基于(势流)涡尾迹方法开发了水平轴风力机叶片气动性能分析程序,采用固定尾迹涡模型和自由尾迹模型分别对气动设计性能进行计算分析,得到风力机设计工况下的涡位置、诱导因子、功率系数及扭矩系数等气动性能参数,并与设计结果对比。结果表明,涡尾迹方法能够快速准确地计算风力机叶片气动性能参数,对风力机叶片气动分析,固定尾迹涡模型较自由尾迹模型计算时间短,具有较好的实用性。     

低雷诺数下柔性翼型气动性能分析

基于流固耦合方法对吸力面5% 至95% 弦长处为三段柔性结构的NACA0012 翼型绕流进行了数值模拟,研究了不同弹性模量下柔性翼型的气动性能和结构响应. 结果表明：在大攻角下,翼面变形影响着翼型表面的非定常流场,起到延缓失速和提高升力的作用;失速后柔性翼的升力系数下降得较为缓慢,且柔性越大,升力系数下降得越平缓;适当减小弹性模量能够提高翼型的气动性能,然而弹性模量过小反而不利于翼型气动性能的提升,并且翼面会产生大幅度的振动.     

3MW叶片翼型设计与气动特性分析

对于大功率叶片的设计研究,翼型的选择和气动特性分析是重要内容。考虑到叶片的整体结构和气动特性,叶片在主要输功区域布置了风力机专用的DU系列翼型,叶尖部分布置NACA64系列翼型,能满足雷诺数较大,阻力小的要求。在确定截面翼型的基础上,结合Wilson理论设计模型初步算出翼型的轴向、周向诱导因子,叶尖、轮毂损失因子等具体...     

基于流固耦合的跨声速压气机叶片静气动弹性分析

采用时域推进的双向流固耦合方法对一级跨声速压气机叶片流场和固体域进行数值模拟,研究跨声速转子叶片静气动弹性变形及其对气动性能的影响,对比分析了100%转速下转子叶片的气动特性和固有频率的变化.结果表明:转子叶片在气动力和离心惯性力共同作用下的弹性变形以扭转变形为主,气动力对叶尖前缘变形量的影响可达总变形量的20%.转子叶片变形后通道流通能力增强,气动特性曲线向大流量方向偏移.     

流固耦合系统动力响应的模态分析理论

本文建立了流固耦合系统动力响应的模态分析理论.首先,从系统的位移-速度势型有限元方程出发,导出了一对具有三个实对称矩阵的广义特征值问题以及两者的相互关系.然后,建立了模态矢量之间的广义正交关系,并通过模态展开,获得了系统对外界激励的响应的封闭解.作为示例,最后给出了两个具体问题的解答.     

ALE动网格法在流固耦合数值模拟中的应用

为了解决流固耦合问题中的物体大幅度运动带来的困难,采用ALE(Arbitrary Lagrange-Euler)动网格方法跟踪自由表面上浮体的运动.计算表明:浮体在无粘流体中的垂荡与弹簧-物体的振动模型理论解符合得较好;浮体在粘性流体中的自由横摇为阻尼运动,其横摇角度随时间的增加而减小,且在不同初始角度下运动系统的固有周期相当.在有外力力矩激励时,外力力矩的周期与系统的固有周期相当时浮体横摇运动趋于共振状态,运动幅度最大.计算结果验证了计算程序的可靠性与精度.本文方法为ALE方法应用于流体-多浮体耦合运动分析奠定了基础.     

漂浮运动对风力机气动特性的影响分析

海上浮式风机为蕴藏丰富的深海风能开发提供了有效的解决方案,浮式基础存在的大幅度纵荡、纵摇和艏摇运动可以改变风轮与流场间的相互作用,从而影响风力机的气动特性。基于叶素-动量理论及其修正方法,以NREL 5MW风力机为研究对象,考虑浮式基础运动对叶片不同径向位置处相对入流风速的影响,提出了风载荷的计算模型,通过编程计算获得了叶轮转矩和风力机功率,并比较了不同运动形式对风力机功率波动的影响。结果表明,纵摇对其功率特性影响最大,这为海上浮式风机的优化设计提供理论依据与数据基础。     

Offshore floating wind turbine and its dynamic problems

Green energy sources and ocean wind power are plentiful in deep sea. More and more offshore wind power plants are constructed in the deep water over hundred meters below the surface. While offshore floating wind turbine system is working, wind turbine, floating foundation, and mooring system affect each other with wind, waves, and currents acting on them. Various offshore floating wind turbine systems and the encountered environmental loads are briefly reviewed and discussed. It is difficult and crucial to comprehensively analyze the aerodynamic-hydrodynamic-service system-structure under the coupling effect of offshore floating wind turbine system. The environmental flow field, structure scale, and rational applications of theories and approaches should be well considered in advance.     

Criterion of aerodynamic performance of large-scale offshore horizontal axis wind turbines

With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic parameters such as the rated wind speed, blade tip speed, and rotor solidity. We show that the essential criterion of a high- performance wind turbine is a highest possible annual usable energy pattern factor and a smallest possible dimension, capturing the maximum wind energy and producing the maximum annual power. The influence of the above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in China＇s offshore meteoro- logical environment is investigated. The variation patterns of aerodynamic and geometric parameters are obtained, analyzed, and compared with each other. The present method for aerodynamic analysis and its results can form a basis for evaluating aerodynamic performance of large-scale offshore wind turbine rotors.     

Research status and trend of wind turbine aerodynamic noise

The main components of the wind turbine aerodynamic noise are introduced. A detailed review is given on the theoretical prediction, experimental measurement, and numerical simulation methods of wind turbine noise, with specific attention to applications. Furthermore, suppression techniques of wind turbine aerodynamic noise are discussed. The perspective of future research on the wind turbine aerodynamic noise is presented.     

螺旋侧板和水深对浮式风机动态响应的影响

为研究漂浮式风力机平台动态响应的优化措施,提出平台附加螺旋侧板的方式。建立基于Spar平台的5MW风力机整机模型,利用有限元软件进行水动力计算,得到不同水深条件下,风力机平台在风、浪、流载荷联合作用下的频域特性,通过与不附加螺旋侧板情况下的动态特性参数对比,探讨螺旋侧板是否对结构的频响特性起到提升作用。结果表明,附加螺旋侧板后,结构的垂荡和纵摇的运动幅值和所受波浪力均得到了显著抑制;与纵荡和纵摇相比,垂荡运动的幅值和所受波浪力所受影响更显著;水深变化对结构响应的幅值有着显著影响。     

Status of large scale wind turbine technology development abroad

To facilitate the large scale (multi-megawatt) wind turbine development in China, the foreign efforts and achievements in the area are reviewed and summarized. Not only the popular horizontal axis wind turbines on-land but also the offshore wind turbines, vertical axis wind turbines, airborne wind turbines, and shroud wind turbines are discussed. The purpose of this review is to provide a comprehensive comment and assessment about the basic work principle, economic aspects, and environmental impacts of turbines.     

复杂工况下的大型风力机气动性能和尾迹研究Investigation of aerodynamic performance and wake of the large scale wind turbine in complicated conditions

在复杂工况下,大型风力机非定常特性会更严重,导致风力机气动性能变化和尾迹预测更加复杂。本文主要针对稳态偏航、动态偏航、风剪切和随机风速场等复杂工况,基于自由涡尾迹方法,嵌入复杂工况的模块,加入了动态失速模型和三维旋转效应模型修正,实现了复杂工况数值模拟计算,比较了不同复杂工况的气动载荷和尾迹形状。最后,得出了风力机在复杂工况下的气动性能、载荷和尾迹叶尖涡线特性,并计算出风力机在复杂工况下的气动载荷超调量和迟滞时间。对推进自由涡尾迹方法应用于风力机工程的大批工况载荷计算,提高大型风力机的载荷计算精度和设计水平等具有重要意义。     

Independent research and development progress in large-scale wind turbine blade with coordinated aerodynamics,structure, and load

Abstract According to the three key elements in blade design process, i.e., aerodynamic design, structure design, and load prediction, the independent research and development (R&D) progress of blade design is summarized and analyzed. The calculational fluid dynamics (CFD) method, the vortex method, and the blade element momentum method (BEM) are described. Based on the widely used BEM method, the solutions for the blade design in low-speed wind area are obtained. A brief overview of the traditional design and analysis methods based on beam models is given. The defects of these methods used for simulating the structure of large-scale composite blade are analyzed. The application progress of the finite element method (FEM) used in the blade structure analysis is shown. The effects of load prediction on the blades and entire wind turbine are introduced. The progress in load forecasting is described. With the analysis of the relationship among these three key elements, it is concluded that developing a blade optimization design system with coordinated aerodynamics, structure, and load will truly meet the requirement of high efficiency and low cost. The main directions for further study are pointed out, e.g., high efficiency and low load airfoils, structural nonlinear finite element analysis, aerodynamic structure coupling research, and establishing different design standards. The aim is to establish a blade R&D system suitable for the conditions of wind resources in China and promote the development of wind power in the country.