风力机叶片多模态耦合振动研究

发布时间：2018-01-12 12:01

本文关键词：风力机叶片多模态耦合振动研究　出处：《西南交通大学》2014年博士论文　论文类型：学位论文

【摘要】：本文系统研究了风力机叶片多模态耦合振动,重点讨论耦合因素(拉弯耦合、高低阶模态耦合、弯弯耦合)对叶片气弹性稳定性、振动特性、非线性动力学行为和稳定性的影响。第1章介绍了本文的研究背景和意义,从叶片动力学模型、气弹性稳定性、振动特性、非线性动力学行为及稳定性等几个方面综述了国内外的研究现状和存在的问题,简述了本文拟开展的工作。第2章综合考虑几何非线性、截面非对称性、倾斜安装、质量偏心、气动偏心、锥角、截面预扭角、结构阻尼、重力、气动力等因素,使用广义哈密顿原理建立了风力机叶片拉伸-挥舞-摆振-扭转耦合非线性振动控制方程。通过和已有模型对比,验证了该模型的准确性和普遍适用性,最后简单讨论了控制方程的求解方法。第3章研究了叶片在耦合非线性振动下的气弹性稳定性问题,为考虑非线性对气弹性的影响,将位移分解为静态位移和动态位移,藉此把非线性项线性化,然后将气弹性稳定性问题转化为复模态问题,并将假设模态法引入到对复模态问题的求解。分析了控制参数对叶片静态变形的影响、挥舞-摆振间的耦合对气弹性稳定性的影响。研究表明：利用挥舞-摆振间的耦合可以改善出现在摆振方向的气弹性不稳定性,但当桨距角很大时,挥舞-摆振耦合反而会造成气弹性不稳定性。第4章研究了非定常气动力作用下叶片耦合振动的动态特性问题,将基于Green函数的数值差分法引入到对变截面叶片耦合振动模态问题的研究,重点考虑了各向振动间的耦合和配重对固有频率和模态的影响。研究表明：高转速时挥舞-摆振间的耦合对弯曲频率影响显著；由于离心刚化效应,弯曲频率随转速的增加而增高；当配重物放置在叶根附近时,配重对频率和模态的影响非常小,但当配重物放置在叶尖处时,配重会显著改变频率和模态振型；配重不改变离心刚化效应。第5章研究了超谐波共振下叶片拉弯(拉伸-挥舞)耦合非线性动力学行为和稳定性。使用多重尺度法求解叶片振动的稳态响应,由雅可比矩阵判断运动稳定性。受非线性因素影响,超谐波共振的共振峰不一定出现在解谐参数σ=0处,本章给出超谐波共振峰对应的解谐参数随设计参数变化的一个近似估计,进而讨论动态响应和稳定性随设计参数和气动因素的变化,该方法可推广到其它类型的共振。拉弯耦合的研究结果表明：轴向拉伸主要表现为静态变形,因此轴向运动对挥舞的影响主要是通过离心刚化效应影响挥舞弯曲固有频率；挥舞对轴向运动动态位移影响非常小,即便在挥舞方向有超谐波共振发生,轴向动态位移也非常小。本章还借助实例分析了不同的设计参数下叶片共振动态响应随气动阻尼的演化,研究表明：对大气动阻尼,叶片响应在共振模态的分量为稳定的单倍外激励周期的响应；随着气动阻尼的减小,非线性影响更加显著,共振模态的周期响应不再稳定且其周期变为多倍外激励周期,最后演化为拟周期响应。第6章研究了挥舞、摆振间的弯弯耦合非线性振动,考虑了经常出现在挥舞和摆振低阶模态的1：2内共振,对非线性控制方程进行Galerkin截断,得到动态位移方程,使用模态变换对刚度项进行解耦,由多重尺度法求解共振稳态响应,讨论了设计参数、风速、几何非线性、气动非线性等因素对共振响应和稳定性的影响。研究表明：正常运转情况下,叶片弯弯耦合振动存在稳定的平凡响应和不稳定的非平凡响应；随风速的增加,叶片耦合振动出现亚临界分叉,非平凡响应消失,平凡响应不再稳定；减弱非线性可使分叉的临界风速升高,进而改善叶片稳定性。第7章研究了内外共振联合作用下挥舞振动高低阶模态间的耦合对叶片非线性动力学行为和稳定性的影响,其中内共振为挥舞前两阶模态间的1：3内共振,外共振为出现在挥舞第一阶模态的主共振。使用多重尺度法求解了组合共振(CR)和单独的主共振(PPR)下叶片稳态振动的动态响应,通过比较CR和PPR的结果分析了内共振(即模态耦合)对外共振的影响,并讨论了外激励、阻尼和非线性因素对两个共振的影响,最后通过实例分析了安装角、锥角、入流速度比等设计参数对共振响应和稳定性的影响。研究表明：内共振对外共振引起的响应和不稳定性具有抑制作用,通过设置高低阶模态间的内共振来控制外共振是合理的。最后,对本文的研究内容、研究方法和研究结果进行了总结,并给出了未来的研究计划。
[Abstract]:This paper studies the multi modal coupling vibration of wind turbine blades, discussed the coupling factors (bending coupling, high order mode coupling, the coupling) on leaf gas elastic stability, vibration characteristics, influence of nonlinear dynamic behavior and stability. The first chapter introduces the research background and significance, from the blade aeroelastic dynamics model. Stability and vibration characteristics, several aspects of nonlinear dynamics and stability of review of the domestic and foreign research situation and existing problems, this paper outlines the work to be undertaken. In the second chapter, considering the geometric nonlinearity, non symmetry section, inclined installation, mass eccentricity, aerodynamic eccentricity, cone angle, pre twist angle structure section. Damping, gravity, aerodynamic force and other factors, a wind turbine blade tension - coupled flap lag torsion vibration control of nonlinear equations using generalized Hamilton principle. And through the existing model Compared to verify the accuracy of the model and general applicability, finally discussed the method for solving the control equation. The third chapter studies the aeroelastic stability problem in nonlinear coupled vibration of blade, considering the influence of nonlinear aeroelastic, displacement can be decomposed into static displacement and dynamic displacement, by linearizing the nonlinear term then, the aeroelastic stability problem is transformed into a complex mode, and the assumed mode method is introduced to solve the problem of complex modal analysis. The effect of control parameters on blade static deformation, influence of flap lag between elastic coupled vibration on gas stability. The research shows that with flap lag between the coupling vibration to improve the stability in the aeroelastic shimmy direction, but when the pitch angle is large, waving shimmy coupling will cause the aeroelastic instability. The fourth chapter studies the unsteady aerodynamic effect The dynamic characteristics of leaves under coupled vibration, the Green function value difference method is introduced into the research of variable cross-section blade modal coupling problem based on considering the coupling influence between the vibration and the weight of each natural frequency and modal. The research showed that the high speed waving effect of coupled vibration between the pendulum bending frequency significantly; due to the centrifugal stiffening effect, bending frequency increases with increasing rotational speed; when the counterweight is placed in near the hub, counterweight to the influence on the resonant frequency and the modal is very small, but when the counterweight is placed on the tip, the weight will significantly change the frequency and modal; weight does not change the centrifugal stiffness effect. The fifth chapter studies the super harmonic resonance of blades under bending (tensile wave) coupling nonlinear dynamic behavior and stability of steady state response. Using the method of multiple scales for blade vibration, by Jacobi matrix judgment Fault movement stability. By nonlinear factors, the resonance peak of super harmonic resonance does not necessarily appear in the detuning parameter =0, a solution of this chapter the harmonic parameters of harmonic resonance peak corresponds with the change of the design parameters of approximate estimation, and then discussed the dynamic response and stability of dynamic factors with the change of design parameters and the. The method can be extended to other types of resonance. The results show that the bending coupling axial tension mainly for static deformation, so the axial motion of the wave is affected mainly by the centrifugal stiffening effect of wave bending natural frequency; wave effect on the axial movement of dynamic displacement is very small, even in the direction of super harmonic resonance wave also, the axial dynamic displacement is very small. This chapter also analyzes with examples with aerodynamic damping evolution, dynamic response of blade resonance under different design parameters on the research shows that: Air damping, blade response stability for single resonance mode excitation component in the cycle; with aerodynamic damping decreases, nonlinear effect is more significant, periodic resonance mode response is no longer stable and its cycle times for the excitation period, finally evolved into a quasi periodic response. The sixth chapter studies the pendulum swing the nonlinear vibration of coupled vibration between the considered frequently appear in the 1:2 internal resonance and waving shimmy of low order modes, the truncated Galerkin nonlinear control equation, the dynamic equation of displacement, stiffness of the decoupling modal transform, response by the method of multiple scales for the steady-state resonance, design parameters, discussed wind speed. The geometric nonlinear effect, aerodynamic nonlinear factors of resonance and stability. The results showed: in normal operating conditions, the stability of the trivial response and curved blade vibration coupling exists Unstable non trivial response; the wind speed increases, the blade coupling vibration of the subcritical bifurcation, non trivial response disappeared, no longer trivial response stability; critical wind speed can make the bifurcation of the nonlinear increase weakened, and improve the blade stability. The seventh chapter studies the internal resonance combined by wave coupled vibration modes of the impact on the level of the nonlinear dynamic behavior and stability of the blade, which is in resonance wielding 1:3 internal resonance between the first two modes, and resonance appears in the main resonance wave of the first order modal. Using multiple scale method combined resonance (CR) and separate primary resonance (PPR) dynamic blade steady vibration response by comparison of CR and PPR results of internal resonance (i.e. modal coupling) affect the external resonance, and discusses the influence of external excitation, damping and nonlinear factors on the two resonance, finally real Example analysis of the installation angle and cone angle, flow velocity ratio design parameters on resonance and stability effects. The results show that: the response caused by the resonance and internal resonance of external instability inhibited by setting the level of internal resonance modes to control external resonance is reasonable. Finally, the research content of in this paper, research methods and research results are summarized, and gives the research plan for the future.

【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM315;O322

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