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风波联合作用下的风力机塔架疲劳特性分析 总被引:1,自引:0,他引:1
研究了海上风力机圆筒型塔架在随机风载荷和波浪载荷作用下的动力响应数值分析方法;建立了基于Palmgren Miner线性累积损伤法则的混泥土塔架安全寿命估计方法.应用线性波理论仿真非规则的海浪,分析作用在圆筒型塔架上的波浪载荷.通过坐标变换,将二维线性波理论扩展为三维线性波理论,建立了波浪力的分析计算模型;用有限元数值分析方法,求解了塔架在风波联合作用下的位移、速度、加速度以及应力响应等;用雨流计数法统计循环参量,将工作循环应力水平等寿命转换成对称循环下疲劳载荷谱,分析了变幅载荷谱下塔架的疲劳损伤及疲劳寿命.算例表明:该文的工作为海上风力机系统气动弹性分析、风力机塔架振动分析和疲劳寿命分析等提供了实用的分析方法. 相似文献
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基于ANSYS软件的参数化设计语言(APDL)开发了风机叶片的几何建模模块,分别构建了风轮,机舱、塔架和基础的海上风机有限元单体和整体模型,并进行了动态特性计算,分析比较了振动模态数值结果,探讨了风机外部荷载作用下的动力效应. 相似文献
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采用多种计算模型结合敏感性分析,研究了塔架及塔架-基础的动力特性,发现塔架与基础的振动有一定的耦合作用;考虑基础与塔架相互作用后,塔架各阶自振频率降低,特别是高阶自振频率降低较多;在地震液化等极端工况下,地基基础对塔架动力特性的影响更明显。总结并分析了塔架的振源,指出脉动风荷载是风力机设计中必须重视的部分;风绕塔架流动一般处于超临界或跨临界范围,在超临界范围不会出现明显的塔架涡激振动,在跨临界范围可能出现严重的振动;风轮属细长弹性体、气动特征明显,其振动响应比较复杂且易发生破坏事故。为减小柔性塔架振幅,给出了风力机起动时快速跳过瞬态共振区、增加塔架阻尼和优化塔架体型以进一步改善塔架动力特性等方面的建议。 相似文献
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水平轴风力机风轮尾迹与圆柱型塔架的相互干涉 总被引:4,自引:0,他引:4
建立了一个考虑上游风轮尾迹与下游塔架相互干涉的物理模型,并进行了详细的数值模拟。基于Navier-Stokes方程,重点研究了上游尾迹与下游圆柱型塔架相互干涉的二维物理特征、旋涡脱落频率、力的脉动与频谱以及纵向位置的影响;计算的流场与水洞进行的激光诱导荧光显示技术的流场显示结果进行了对比;在相同的横向位置和来流条件下,获得了处于不同纵向位置的干涉结果。研究结果对于揭示风力机风轮尾迹与下游塔架相互干涉的物理机理,减少由于位势干涉和尾迹粘性所诱导的非定常气动力,以及对于风力机的气动弹性稳定性和噪声辐射的研究等都有着重要的理论价值。 相似文献
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The aeroelastic response and the airloads of horizontal-axis wind turbine rotor blades were numerically investigated using a coupled CFD–CSD method. The blade aerodynamic loads were obtained from a Navier–Stokes CFD flow solver based on unstructured meshes. The blade elastic deformation was calculated using a FEM-based CSD solver which employs a nonlinear coupled flap-lag-torsion beam theory. The coupling of the CFD and CSD solvers was accomplished in a loosely coupled manner by exchanging the information between the two solvers at infrequent intervals. At first, the present coupled CFD–CSD method was applied to the NREL 5MW reference wind turbine rotor under steady axial flow conditions, and the mean rotor loads and the static blade deformation were compared with other predicted results. Then, the unsteady blade aerodynamic loads and the dynamic blade response due to rotor shaft tilt and tower interference were investigated, along with the influence of the gravitational force. It was found that due to the aeroelastic blade deformation, the blade aerodynamic loads are significantly reduced, and the unsteady dynamic load behaviors are also changed, particularly by the torsional deformation. From the observation of the tower interference, it was also found that the aerodynamic loads are abruptly reduced as the blades pass by the tower, resulting in oscillatory blade deformation and vibratory loads, particularly in the flapwise direction. 相似文献
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采用CFD方法,以NH1500三叶片大型水平轴风力机为研究对象,研究额定风速剪切来流下的塔影效应对水平轴风力机叶片和风轮非定常气动载荷的影响。结果表明:剪切来流下,叶片和风轮的气动载荷均呈余弦变化规律,塔影效应的主要影响叶片方位角范围为160°~210°,且该范围不随风剪切指数的变化而变化。相同风剪切指数下,塔影效应对叶片和风轮气动载荷的均方根影响较小,对其波动影响较大。当风剪切指数从0.12增至0.30时,塔影效应下,叶片气动载荷的均方根减小,推力和转矩的波动幅度增大,偏航力矩和倾覆力矩的波动幅度减小;风轮推力和转矩的均方根减小,波动幅度变化较小,而倾覆力矩和偏航力矩的均方根增大,且波动幅度也增大。 相似文献
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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。 相似文献
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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. 相似文献
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Dynamic behavior of wind turbines influenced by aerodynamic damping and earthquake intensity 下载免费PDF全文
In the present paper the effects of aerodynamic damping and earthquake loads on the dynamic response of flexible‐based wind turbines are studied. A numerical analysis framework (NAF) is developed and applied. NAF is based on a user‐compiled module that is developed for the purposes of the present paper and is fully coupled with an open source tool. The accuracy of the developed NAF is validated through comparisons with predictions that are calculated with the use of different numerical analysis methods and tools. The results indicate that the presence of the aerodynamic loads due to the reduction of the maximum displacement of the tower attributed to the dissipation of earthquake excitation energy in fore‐aft direction. Emergency shutdown triggered by strong earthquakes results to a rapid change of aerodynamic damping, resulting to short‐term instability of the wind turbine. After shutdown of the wind turbine, enhanced dynamic response is observed. For the case where the wind turbine is parked, the maxima displacement and acceleration of tower‐top increase linearly with the peak ground acceleration. With the use of the least‐square method a dimensionless slope of tower‐top displacements is presented representing the seismic response coefficient of tower that can be used to estimate the tower‐top acceleration demand. Moreover, on the basis of the seismic response coefficient, an improved model for the evaluation of load design demand is proposed. This model can provide accurate predictions. 相似文献
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Vincent Leroy Jean‐Christophe Gilloteaux Mattias Lynch Aurlien Babarit Pierre Ferrant 《风能》2019,22(8):1019-1033
Over the last decade, several coupled simulation tools have been developed in order to design and optimize floating wind turbines (FWTs). In most of these tools, the aerodynamic modeling is based on quasi‐steady aerodynamic models such as the blade element momentum (BEM). It may not be accurate enough for FWTs as the motion of the platform induces highly unsteady phenomena around the rotor. To address this issue, a new design tool has been developed coupling a seakeeping solver with an unsteady aerodynamic solver based on the free vortex wake (FVW) theory. This tool is here compared with the reference code FAST, which is based on the BEM theory in order to characterize the impact of the aerodynamic model on the seakeeping of a floating horizontal axis wind turbine (HAWT). Aerodynamic solvers are compared for the case of the free floating NREL 5MW HAWT supported by the OC3Hywind SPAR. Differences obtained between the models have been analyzed through a study of the aerodynamic loads acting on the same turbine in imposed harmonic surge and pitch motions. This provides a better understanding of the intrinsic differences between the quasi‐steady and unsteady aerodynamic solvers. The study shows that differences can be observed between the three aerodynamic solvers, especially at high tip speed ratio (TSR) for which unsteady aerodynamic phenomena and complex wake dynamics occur. Observed discrepancies in the predictions of the FWT dynamic response can raise issues when designing such a system with a state‐of‐the‐art design tool. 相似文献
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The aerodynamic loads for MW scale horizontal-axis wind turbines are calculated and analyzed in the established coordinate systems which are used to describe the wind turbine. In this paper, the blade element momentum (BEM) theory is employed and some corrections, such as Prandtl and Buhl models, are carried out. Based on the B-L semi-empirical dynamic stall (DS) model, a new modified DS model for NACA63-4xx airfoil is adopted. Then, by combing BEM modified theory with DS model, a set of calculation method of aerodynamic loads for large scale wind turbines is proposed, in which some influence factors such as wind shear, tower, tower and blade vibration are considered. The research results show that the presented dynamic stall model is good enough for engineering purpose; the aerodynamic loads are influenced by many factors such as tower shadow, wind shear, dynamic stall, tower and blade vibration, etc, with different degree; the single blade endures periodical changing loads but the variations of the rotor shaft power caused by the total aerodynamic torque in edgewise direction are very small. The presented study approach of aerodynamic loads calculation and analysis is of the university, and helpful for thorough research of loads reduction on large scale wind turbines. 相似文献
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Verifying the Blade Element Momentum Method in unsteady,radially varied,axisymmetric loading using a vortex ring model 下载免费PDF全文
Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineering dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi‐steady state and annuli independence of the blade element momentum theory for unsteady, radially varied, axi‐symmetric load cases is investigated. Firstly, a free wake model that combines a vortex ring model with a semi‐infinite cylindrical vortex tube was developed and applied to an actuator disc in three load cases: (i) steady uniform and radially varied, (ii) two types of unsteady uniform load and (iii) unsteady radially varied load. Results from the three cases were compared with Momentum Theory and also with two widely used engineering dynamic inflow models—the Pitt‐Peters and the Øye for the unsteady load cases. For unsteady load, the free wake vortex ring model predicts different hysteresis loops of the velocity at the disc or local annuli, and different aerodynamic work from the engineering dynamic inflow models. Given that the free wake vortex ring model is more physically representative, the results indicate that the engineering dynamic inflow models should be improved for unsteady loaded rotor, especially for radially varied unsteady loads. © 2016 The Authors. Wind Energy Published by John Wiley & Sons, Ltd. 相似文献