【作者】 陈小波；

【导师】 陈健云；

【作者基本信息】 大连理工大学 ， 结构工程， 2011， 博士

【摘要】 近年来随着能源危机和环境问题的凸显,海上新能源的开发和利用受到了世界各国越来越多的关注。2010年我国成功的建设了上海东海大桥近海风力发电场,它的成功建设标志着我国已进入了海上风力发电时代。随着我国近海风力发电场的建设,越来越多的工程问题摆在了我国工程人员和科研人员的面前。目前,我国还没有近海风机结构设计方面专业性的规范,近海风力发电场的建设和技术在我国尚处在起步阶段。因此,系统的研究近海风机结构体系在海洋环境荷载作用下的动力反应问题对于我国兴建大型海上风力发电场是十分有意义的。本文从近海风机环境模拟和海洋环境荷载作用下近海风机结构体系的动力反应分析两方面入手,系统的研究了近海风机结构随机风荷载、随机波浪荷载和非线性波流荷载的计算方法,并在时域内分析了近海风机在气动力荷载和水动力荷载作用下的动力反应,在频域内基于虚拟激励法研究了近海风机结构体系随机振动的分析方法。结合新型无网格数值方法-光滑粒子流体动力学方法(SPH)在三维条件下模拟了波浪对风机塔架-基础的冲击过程,基于SPH和FEM耦合算法研究了波浪与近海风机塔架-基础的动力相互作用问题。本文的具体研究工作如下：(1)近海风能利用及近海风机结构体系动力反应研究综述。从课题研究背景入手,分析了在我国大力开发近海风能发电背景下,系统研究近海风机结构动力特性的意义和必要性。介绍了目前国内外近海风能发电的利用现状,及其所产生的经济效益和环保效益。从土木工程领域出发,介绍了近海风机结构体系的分类,综述了近海风机结构体系环境荷载计算、近海风机叶片动力反应分析和近海风机塔架-基础动力反应分析国内外的研究现状。(2)近海风机叶片气动荷载及叶片动力特性研究。基于叶素动量理论研究了考虑脉动风的风轮气动荷载的计算方法,同时探讨了风机转速对风轮荷载的影响规律,分析了风轮在不同转速下对风机塔架的最不利作用。建立了变截面悬臂梁风机叶片简化模型,通过与实际叶片模态振型和模态频率的对比验证了采用变截面悬臂梁模型进行动力分析的可行性。探讨了叶片离心刚化效应对风机叶片自身动力特性的影响规律,通过引入叶片轴力面和自振频率面直观的分析了叶片自振频率与时间和转速之间的关系,同时通过引入刚化系数的概念定量的研究了旋转叶片的离心刚化效应,并探讨了考虑离心刚化效应的叶片基频修正公式。(3)气动荷载作用下近海风机动力反应研究。针对近海风机的体型特征,提出了考虑空间相干效应的近海风机脉动风模拟方法,通过计算谱和目标谱的比较验证了模拟方法的正确性。在时域内研究了考虑叶片-塔架动力耦合效应时塔架的动力响应特性,探讨了叶片-塔架动力耦合效应对塔架风振响应的影响规律。在时域内研究了考虑叶片刚化效应时近海风机叶片和塔架的动力响应特性,探讨了旋转叶片产生离心刚化效应对风机叶片和塔架风振响应的影响规律。(4)气动力荷载和水动力荷载联合作用下近海风机动力反应研究。研究了近海风机随机波浪荷载的计算方法,在时域内分析了近海风机在随机风浪联合作用下的动力反应,定量的探讨了波浪荷载组合机制和波面变化等因素对近海风机环境荷载计算和动力响应计算的影响规律。基于流函数理论研究了近海风机非线性波浪荷载的计算方法,在时域内分析了近海风机在风与非线性波浪联合作用下的动力反应,定量的探讨了波面变化、桩径和波浪非线性等因素对近海风机非线性波浪荷载计算和动力响应计算的影响规律。基于流函数理论研究了考虑波流相互作用的近海风机非线性波流荷载计算方法,在时域内分析了近海风机在风与非线性波流荷载联合作用下的动力反应,探讨了不同波流相互作用模型和波流概率组合模型对近海风机非线性波流荷载的影响规律。(5)基于虚拟激励法的近海风机随机动力反应研究。分析了虚拟激励法的基本理论,基本计算过程,为研究虚拟激励法在近海风机结构随机振动分析上的应用奠定了基础。提出了基于虚拟激励法的近海风机结构体系随机振动高效算法,针对近海风机结构体型特征提出了近海风机结构体系虚拟激励力的构造方法和位移反应谱的计算方法,并通过空间相关函数考虑了虚拟激励力的空间相干效应。基于本文的计算方法研究了频域内近海风机叶片和塔架在风荷载激励下的随机振动问题,计算叶片和塔架位移反应功率谱和设计基准期内的极值。通过引入虚拟激励法解决了大型近海风机结构的随机振动高效计算问题,可为实际工程提供借鉴和参考。(6)基于SPH理论的近海风机结构与波浪动力相互作用研究。提出了基于SPH和FEM耦合算法的近海风机动力反应及波浪-结构动力相互作用的分析方法,其中包括SPH数值波浪槽和近海风机塔架-基础的三维动力分析模型的建立方法,及SPH和FEM耦合算法的计算流程。在三维条件下实现了基于SPH方法的波浪对塔架-基础冲击过程的数值模拟,计算了冲击过程中波浪速度场和压力场的变化情况。基于SPH和FEM耦合算法研究了波浪作用下近海风机塔架-基础的动力反应,并在三维条件下实现了包含波浪-结构的动力相互作用的近海风机塔架-基础的动力反应分析。更多还原

【Abstract】 In recent years, with energy crisis and environmental problem breaking out, the development and exploitation of marine renewable energy receive more and more attention around the world. China successfully constructed the Shanghai East Sea Bridge offshore wind farm in 2010, which marks that China has entered the offshore wind power times. As China’s construction of offshore wind farms, more and more engineering problems are placed in front of our engineers and scientists. At present, our country still has no professional structural design standard of offshore wind turbine. The construction and technology of offshore wind farm in China are still in its initial stage. Therefore, systematically study the dynamic response of offshore wind turbine structural system under marine environmental loads will be very meaningful for our country to construct large offshore wind farms.This paper started from two aspects, one is marine environmental loads simulation and the other one is the dynamic response analysis of offshore wind turbine under marine environmental loads. The calculation method of random wind loads, random wave loads and nonlinear wave and currents loads of offshore wind turbine were studied systematically. The dynamic responses of offshore wind turbine under aerodynamic and hydrodynamic loads were studied in time domain. The analysis method of random dynamic response of offshore wind turbine was studied based on pseudo excitation method in frequency domain. The wave impact on the offshore wind turbine tower-foundation process was simulated in three-dimensional based on the new mesh-free method-smooth particle hydrodynamics (SPH). The wave and offshore wind turbine tower-foundation interaction problems were studied based on the SPH and FEM coupling method. Specific studies of this paper are as follows:(1) Review of the offshore wind energy utilization and dynamic response analysis of offshore wind turbine structural systems. This paper started from the research background, it is very meaningful and necessary to study the dynamic response of offshore wind turbine structural system systematically under the background that our country are vigorously developing the offshore wind power in current. The current domestic and international offshore wind energy utilization and the resulting economic and environmental benefits were introduced first in the paper. Starting from the field of civil engineering, structural classification of the offshore wind turbine was introduced. And then the current status of the environmental load calculation method of offshore wind turbine structural system and dynamic response analysis of offshore wind turbine blades, tower and foundation were reviewed in the paper.(2) Research on the aerodynamic loads of offshore wind turbine blade and dynamic characteristics of blades. The aerodynamic loads of blades were studied based on blade element momentum theory (BEM) with considering the fluctuating wind speed. The blade rotating speed influence on the aerodynamic loads of blade was studied, and then the most adverse action of the blades on the tower was analyzed. The variable cross-section cantilever beam model was built for offshore turbine blade as a simplified model. The feasibility of introducing the variable cross-section cantilever beam model for dynamic analysis was verified by comparison of the modal shapes and modal frequency. The centrifugal stiffening effect influence on the dynamic characteristics of blades were studied, and the axial force plane and natural frequency plan of blade were introduced to analyze the relationship between natural frequency, time and rotating speed directly. By introducing the concept of coefficient, the centrifugal stiffening effect was studied quantitatively.(3) The dynamic response study of offshore wind turbine under aerodynamic loads. Contrary to the outline characteristics of offshore wind turbine, the simulation method of fluctuating wind with considering the spatial coherence effect was presented based on the harmonic superposition method. The correctness of the simulation method was validated by comparison of the calculation spectrum and target spectrum. The dynamic response of offshore wind turbine with considering the blade and tower coupling effect was study, and the influence of the blade and tower coupling effect on the wind induced response of tower was discussed. The paper also studied the dynamic response of offshore wind turbine with considering the centrifugal stiffening effects, and the influence of the centrifugal stiffening effects on the wind induced response of blade and tower were also studied in this paper.(4) Research on the dynamic response of offshore wind turbine under aerodynamic and hydrodynamic loads. The calculation method of random wave loads was studied, and the dynamic responses of offshore wind turbine under random environmental loads were analyzed in time domain. The influence on the environmental loads results and the dynamic response of offshore wind turbine of loads combination rules and free surface variation were discussed quantitatively. Based on the stream function wave theory, the nonlinear wave loads calculation method of offshore wind turbine was studied, and the influence of wave surface variation and pile diameters on the nonlinear wave loads were discussed quantitatively. Then the dynamic responses of offshore wind turbine under nonlinear wave loads were calculated. The nonlinear wave and currents loads of offshore wind turbine were also studied by the stream function wave theory, and the dynamic responses of offshore wind turbine under nonlinear wave loads were calculated in time domain. The influences of wave and current interaction model and wave-current combination model on the nonlinear wave current loads were investigated.(5) Study on random dynamic response of offshore wind turbine based on the pseudo excitation method. The basic theory and calculation process of pseudo excitation method were analyzed first, and it lays a foundation to study the pseudo excitation method application on analyzing the random dynamic of offshore wind turbine. The high performance calculation method of offshore wind turbine random dynamic analysis was presented based on the pseudo excitation method. Based on the structural characteristics of offshore wind turbine, the pseudo excitation load construction method of blade and tower and the calculation method of displacement power spectrum were presented. The spatial coherence of pseudo excitation load was studied by the spatial coherence function.Based on the calculation method presented in this paper, the random vibration response of wind turbine blade and tower under wind loads were analyzed in frequency domain, and the displacement power spectrum of offshore wind turbine blade and tower and the extreme response values in design life period were calculated. By introducing the pseudo excitation method, the random vibration analysis of large scale offshore wind turbine was solved efficiently, and it can provide a reference to the engineering project.(6) Study on the offshore wind turbine and wave interaction problem based on SPH method. The analysis method of offshore wind turbine dynamics and wave-structure interaction was presented based on the SPH and FEM coupling method, which includes SPH and FEM coupling method calculation process and the construction methods of numerical wave tank and three dimensional dynamic analysis models of offshore wind turbine tower and foundation. The wave impact process on the tower was simulated based on the SPH method and the velocity field and pressure field of fluid during the impact process were calculated. By combining the SPH and FEM coupling method, the dynamic response of offshore wind turbine tower and foundation and their response with considering the wave-structure interaction effect were studied in three three-dimensional.更多还原