风力机叶片高升力系数法的气动设计研究

在动量-叶素理论和Betz理论的基础上,结合PROPID软件进行功率为1.5 MW水平轴风力机叶片的气动设计研究。叶片气动设计采用高升力系数法,叶片剖面采用NPU-WA系列高升力、高升阻比风力机专用翼型,在叶片性能预测中采用叶尖损失、轮毂损失和Viterna失速模型。设计结果表明采用先进风力机翼型并运用高升力系数法设计的大功率风力机叶片的弦长较小,叶片面积较小,有利于减轻叶片的重量,同时降低制造成本。     

基于双盘面多流管模型的升力型风轮气动性能改善分析

在单个叶片旋转一周内存在两个方位角(0°~180°),其当地攻角为零,当地力矩为负值,当地功率输出为负值,降低了风轮整体性能。提出采用扰流来改善两个方位角叶片周围流场,进而提高风轮整体气动性能的新方法。以美国Sandia国家实验室旋转直径2 m的Φ型风轮为研究对象,基于双盘面多流管模型,分析扰流对风轮上盘面和下盘面的气动攻角和力矩以及整体气动性能的影响规律。计算结果证明:在扰流的影响下,0°方位角的气动攻角从0°提高到5°,叶素力矩从0.2 Nm提高到1.1 Nm,风轮的风能利用系数提高8%;在180°方位角增设扰流后,其气动特性提高幅度较0°方位角低,叶素力矩最大增幅为0.4 Nm,风轮的风能利用系数提高3%。经验证双盘面多流管模型计算结果与Sandia试验结果吻合良好,证明计算结果具有可参考性。     

基于一种新的优化方法的水平轴风力机风轮设计软件

提出了一种用于水平轴风机风轮设计的软件。该软件的主要目的是为风力机设计者提供一种灵活的集成设计环境，其核心是一个水平轴风机的气动优化过程。该过程基于一种改进的叶素理论，它采用一个有限叶片的旋涡系，因此叶片数量的影响被考虑进行并可得到更精确的气动力。     

200kW水平轴风力机叶片气动外形设计与性能分析

基于Glauert漩涡理论,考虑了风轮涡流系的影响,引入轴向和切向诱导因子,结合具体的工程实际,以此完成了200 k W风力机叶片的气动外形设计。并在此基础上,运用BLADED软件对其气动性能进行了分析,结果表明该风力机叶片的气动性能达到了设计要求,且具有较高的风能利用系数。该分析结果为风力机叶片气动外形优化设计和结构设计的进一步研究奠定了基础。     

风力发电机叶片设计与气动性能仿真研究

运用叶素理论和气动理论,基于设定的风力机性能参数对风轮叶片进行三维设计。利用Gambit建模软件对风力机单叶片进行三维建模,再用Fluent软件进行风力机叶片气动性能的数值模拟,仿真叶片气动流场流态,并计算叶轮的升力、阻力和扭转力矩;验证风力机气动性能数值模拟的可行性和可靠性;计算发电机组功率和风能利用效率等性能参数。对风力发电机叶片的设计和气动数值模拟计算分析的工作可深化对风力发电机组三维叶片的气动性能的了解,仿真风力发电机组气动流场,能为风力机叶片的设计、改型和研发工作提供技术参数和指导意见。     

基于泛模型的风轮不平衡载荷控制

针对大型变速变桨风电机组风轮的非线性特征和难以建立精确模型的问题,设计了一种基于泛模型的风轮不平衡载荷自适应控制器。根据传感器测量的叶根载荷,对3个叶片进行独立变桨控制,通过3个叶片的桨距角差异来减小风轮的不平衡载荷。在此基础上,以双馈变速变桨机组为对象,通过仿真对该控制器进行了测试,结果表明该方法用于减小风轮的不平衡载荷是可行且有效的。     

圆弧形叶片风轮气动设计的研究

本文以风轮旋涡理论和动量理论为基础，用复变函数中的保角映射法把圆弧形叶片映射成圆，以圆柱绕流理论求解风轮诱导速度场，并从局部风能利用系数最大值出发，推证出圆弧形叶片风 气动设计方法。     

大型风力机风轮气动不平衡的特性研究与验证

为了研究和探索风轮气动不平衡的物理特性,以某2.0 MW三叶片水平轴风力机为研究对象,采用计算机仿真及试验相结合的方法,研究风轮气动不平衡对机组动力学特性、气动性能及气动载荷的影响研究。通过气动特性分析和动力学分析表明,随着风轮叶片安装角的不平衡度增大,其机组性能逐渐下降,塔顶的载荷波动逐渐增大,叶片的挥舞载荷出现明显差异,机舱振动加速度变大。对塔顶振动加速度进行快速傅里叶变换分析,出现明显特征变化。研究过程表明,监测机舱振动加速度和机组功率曲线能有效识别机组气动不平衡程度。     

变速变桨距风力发电机气动特性研究

基于动量叶素理论,考虑了叶尖损失、风轮锥角以及修正的轴向和切向诱导因子等因素的影响,推导出速度诱导因子的迭代计算公式。考虑了影响风力发电机气动性能的各种因素,较为准确地建立了风轮计算模型。结合实例计算分析了速度诱导因子及叶片受力沿叶片展向的分布规律,分析了桨距角、转速和叶尖速比等参数对风力机气动特性的影响,得到风力发电机的气动特性曲线。在此基础上,分析了提高风力机风能利用率和减小载荷波动的方法,为风力发电机的动态设计及运行特性分析奠定了基础。     

风力机叶片三维数值计算方法确认研究

采用CFD软件包FINETM/TURBO,以两叶片NREL PhaseⅥ风力机的风轮为对象,进行了风力机风轮叶片三维绕流的定常粘性数值模拟研究。通过详细对比计算结果与实验数据(包括功率、叶片展向5个截面压力系数分布及沿叶展方向载荷系数分布),确认在大部分风速条件下数值模拟可以很好的预计风力机气动性能。然后分析了计算域尺度、边界条件和湍流模型等对数值模拟结果的影响,为采用CFD技术对实际风力机叶片三维气动性能进行精确数值模拟提供参考。     

小型变桨距风力机的气动优化设计

基于叶素动量理论分析了小型风力机的气动性能分析模型,并提出了叶片的气动优化设计方法.结合叶片制造和应用中的实际要求,设计了10 kW小型变桨距风力机叶片的气动外形.计算结果表明,设计叶片具有良好的气动性能,验证了该设计方法有效实用.     

定桨距风力机气动优化设计优化方向分析

简述风力气动优化设计的模型和方法，分析定桨距风力机桨叶外形变化对气动性能的影响，指出气动优化设计应考虑的优化目标和主要参数，并根据该方法对２００ｋＷ定桨距风力机进行了气动优化设计，给出优化结果并加以分析比较。     

The inverse design of the wind turbine blade sections by the singularities method

The aerodynamic characteristics of wind turbines are closely related to the geometry of their blades. The innovation and the technological development of wind turbine blades can be centred on two tendencies. The first is to improve the shape of existing blades; the second is to design new shapes of blades. The aspiration in the two cases is to achieve an optimal circulation and hence enhancing some more ambitious aerodynamic characteristics. This paper presents an inverse design procedure, which can be adapted to both thin and thick wind turbine blade sections aiming to optimise the geometry for a prescribed distribution of bound vortices. A method for simulating the initial contour of the blade section is exposed, which simultaneously satisfy the aerodynamic and geometrical constraints under nominal conditions. A detailed definition of the function characterising the bound vortex distribution is presented. The inviscid velocity field and potential function distributions are obtained by the singularities method. In the design method implemented, these distributions and the circulation of bound vortices on the camber line of the blade profile, are used to rectify its camber in an iterative calculation leading to the final and optimal form of the blade section once convergence is attained. The scheme proposed has been used to design the entire blade of the wind turbine for a given span-wise distribution of bound circulation around the blade contour.     

Inverse design of horizontal axis wind turbine blades using a vortex line method

A new inverse design process for horizontal axis wind turbine blades is developed to account for three‐dimensional blade features such as non‐planar wing tip. The multidimensional Newton iteration method combined with a vortex line method is used to provide blade geometry parameters given desired aerodynamic behaviors such as lift coefficient and axial induction. The Jacobian matrix is visualized to show the effect of the change of the blade twist and chord on the change of the aerodynamic behaviors. The method is validated for a canonical straight blade with uniform lift coefficient and axial induction distributions. The results show an excellent agreement with those obtained by PROPID, which is a blade element momentum theory‐based inverse design code. The National Renewable Energy Laboratory Phase VI blade is used to validate the method for a straight blade with non‐uniform distributions of the lift coefficient and axial induction. The method is also applied successfully to a non‐straight blade design with a non‐planar wing tip. A noticeable change in the twist and chord for this non‐straight blade is seen compared with a straight blade. Finally, the inverse design code is used to make a large rotor blade, and the power output generated by this blade is computed. Copyright © 2014 John Wiley & Sons, Ltd.     

Fluid structure interaction of a morphed wind turbine blade

One serious challenge of energy systems design, wind turbines in particular, is the need to match the system operation to the variable load. This is so because system efficiency drops at off‐design load. One strategy to address this challenge for wind turbine blades and obtain a more consistent efficiency over a wide load range, is varying the blade geometry. Predictable morphing of wind turbine blade in reaction to wind load conditions has been introduced recently. The concept, derived from fish locomotion, also has similarities to spoilers and ailerons, known to reduce flow separation and improve performance using passive changes in blade geometry. In this work, we employ a fully coupled technique on CFD and FEM models to introduce continuous morphing to desired and predetermined blade design geometry, the NACA 4412 profile, which is commonly used in wind turbine applications. Then, we assess the aerodynamic behavior of a morphing wind turbine airfoil using a two‐dimensional computation. The work is focused on assessing aerodynamic forces based on trailing edge deflection, wind speed, and material elasticity, that is, Young's modulus. The computational results suggest that the morphing blade has superior part‐load efficiency over the rigid NACA blade. Copyright © 2013 John Wiley & Sons, Ltd.     

New vortex‐lift and tangential‐force models for HAWT aerodynamic load prediction

Horizontal axis wind turbines (HAWTs) experience three‐dimensional rotational and unsteady aerodynamic phenomena at the rotor blades sections. These highly unsteady three‐dimensional effects have a dramatic impact on the aerodynamic load distributions on the blades, in particular, when they occur at high angles of attack due to stall delay and dynamic stall. Unfortunately, there is no complete understanding of the flow physics yet at these unsteady 3D flow conditions, and hence, the existing published theoretical models are often incapable of modelling the impact on the turbine response realistically. The purpose of this paper is to provide an insight on the combined influence of the stall delay and dynamic stall on the blade load history of wind turbines in controlled and uncontrolled conditions. New dynamic stall vortex and nonlinear tangential force coefficient modules, which integrally take into account the three dimensional rotational effect, are also proposed in this paper. This module along with the unsteady influence of turbulent wind speed and tower shadow is implemented in a blade element momentum (BEM) model to estimate the aerodynamic loads on a rotating blade more accurately. This work presents an important step to help modelling the combined influence of the stall delay and dynamic stall on the load history of the rotating wind turbine blades which is vital to have lighter turbine blades and improved wind turbine design systems.     

双层翼水平轴风力机气动性能研究

以NREL Phase VI风力机叶片为参照对象,设计一种双层翼叶片.在不同来流风速下,对该新型水平轴风力机叶片气动性能进行数值模拟,对比原始NREL Phase VI风力机在相同来流风速相同叶片高度处的流线图,发现双层翼叶片可较有效抑制流动分离.进一步将双层翼风力机叶片的扭矩值、弯矩值分别与相同条件下NREL Pha...     

Efficient incorporation of fatigue damage constraints in wind turbine blade optimization

Wind turbine design is a challenging multidisciplinary optimization problem, where the aerodynamic shapes, structural member sizing, and material composition must all be determined and optimized. Some previous blade design methods incorporate static loading with an added safety factor to account for dynamic effects. Others incorporate dynamic loading, but in general limit, the evaluation to a few design cases. By not fully incorporating the dynamic loading of the wind turbine, the final turbine blade design is either too conservative by overemphasizing the dynamic effects or infeasible by failing to adequately account for these effects. We propose an iterative method that estimates fatigue effects during the optimization process while quickly converging to the true solution. We also demonstrate an alternate approach where a surrogate model is trained to efficiently estimate the dynamic loading of the wind turbine in the design process. This surrogate model, once trained, was then incorporated in the optimization loop of the wind turbine blade. In contrast to the iterative method, there is significant upfront computational cost to construct the surrogate model. However, this surrogate model has been generalized to be used for different rated turbines and can predict the fatigue damage of a wind turbine with less than 5% error for baseline wind turbines of the same family. These methods can be used instead of the more computationally expensive method of calculating the dynamic loading of the turbine within the optimization routine.     

A wind turbine blade profile analysis code based on the singularities method

The aerodynamic characteristics of wind turbines are closely related to the geometry of their blade profiles. The innovation and the technological development of wind turbine blade profiles can be centred on two tendencies. The first is to improve the shape of the existing airfoils and the second is to design new shapes of airfoils in order to get some more ambitious aerodynamic characteristics and enhanced performance.The aim of this paper is to develop an accurate airfoil analysis lower order code, based on the singularities method, for wind turbine applications. The 2D incompressible potential flow model has been used. In the implementation of the singularities method, source–vortex distributions over the airfoil contour are used to compute the flow characteristics. The accuracy and the validity of the results have been tested using experimental data obtained from Wind Turbine Airfoil Catalogue “Risø National Laboratory, Roskilde, Denmark, August 2001” and have shown considerable agreement.     

百千瓦中型变速变桨风电机组叶片设计研究

百千瓦级叶片一般采用定桨方式运行,依靠叶片失速进行功率控制,机组运行过程中无法维持较高的效率。基于100 kW变速变桨机组的运行特征,提出了一种100 kW级中型叶片的设计方法。气动设计采用了BEM方法,利用Harp_opt中的优化算法获得较高的气动性能;结构及载荷设计参考IEC标准进行,采用Focus进行铺层设计及结构特性分析。所设计叶片的长度为10.029 m左右,极限及疲劳载荷特性满足GL IIA类风场的运行要求。