海流能发电涡激振动驱动的水动力特性及能量获取研究

发布时间：2018-05-09 20:01

本文选题：海流 + 涡激振动　；参考：《昆明理工大学》2016年博士论文

【摘要】：在不可再生能源日益枯竭、且对环境危害压力越来越大,但能源需求却不断增长的今天,寻找、开发新型清洁能源替代化石能源的需求越来越受到重视。海洋潮流能作为一种绿色可再生能源,具有可持续性、高能源密度、丰富蕴藏量等特点,使其成为有广阔发展前景的开发领域。流速较低的海流能为潮流能的一种,其能量密度与流速的立方成正比,若采用传统的水下涡轮机驱动系统,由于水力涡轮在海流环境下很难像风力机那样较为灵活地实现有效能量转换,基于流体力学圆柱绕流涡激振动的驱动模式成为一种选择。涡激振动利用均匀流下圆柱涡脱落力诱发其共振的机理捕获海流能,以此形成水力驱动系统进行发电,是一种适于低速海流环境的水力驱动发电方式。本文重点研究了海流环境下诱发涡激振动的参数范围及系统最大获能的海流环境,并通过流固耦合数值方法对涡激振动进行了数值研究,对影响涡激振动获取能量的最佳参数进行了分析,设计了具有不同横向和流向间距比、不同布置方式的多圆柱振动系统作为能量转换装置,详细分析研究了系统涡激振动响应、水动力特性、尾涡模式以及能量获取效率和能量密度大小与系统参数的关系。主要研究内容和创新成果如下：(1)采用了一种能较好模拟涡激大幅振动的流固双向耦合数值方法。计算模型流体区域使用基于任意拉格朗日-欧拉(ALE)动网格机制的不可压缩雷诺时均RANS方程描述,并用SSTk-ω湍流模型进行封闭,采用基于ADNA系统开发的FCBI-C单元模式离散计算区域,配合相应的算法,实现了涡激振动圆柱体大幅振动情况下尾流涡街形成的高效数值模拟,得到了不同约化速度下系统的响应分支、振幅、频率、相位角、流场信息以及各响应分支中的尾涡脱落特征。通过文献对比研究,证明本文提出的分析理论和数值方法是高效可靠的,可很好地用于模拟单圆柱或多圆柱系统的涡激振动。(2)提出了基于涡激振动获取海流能发电的4种参数方案,分别研究了各方案质量比m*、阻尼比ζ质量阻尼比m*ζ和水中固有频率fm,w对单圆柱涡激振动响应及能量转换效率η的影响,给出不同方案下各参数在基于海流水动能获取应用中的最佳适应范围。研究发现,质量比m*和阻尼比ζ除了影响能量转换效率η,还影响有效获取能量的约化速度范围,不同系统均存在最优的质量阻尼比m*ζ值,使最大能量转换效率ηmax值和平均能量转换效率ηp值最大。研究还发现,适当设计系统的fn,w值,不仅可使圆柱从水流中获取能量效率最大,同时还可使圆柱结构在较广的流速和约化速度范围内都能获取较高的水动能。(3)研究了间距比对矩形布置的四圆柱振动系统的水动力特性及其对获取海流能效率的影响,并且从规模化开发利用海流能的角度考虑,能量转换器应优先考虑由多个圆柱组成的系统。本文提出了一种结合并列和串列构形的矩形布置四圆柱振动系统,并首次提出机械耦合的概念描述这种系统的动态特性,即将由四个圆柱组成的振动系统整体视为一个质量-弹簧-阻尼系统,任何响应时刻,维持振动系统中的四圆柱相对位置始终保持不变,以便系统获得最佳的水动力特性。由于机械耦合的四圆柱振动系统为矩形布置,横向和流向间距比不同,提出组合间距比LH/D2这一概念。通过四柱机械耦合系统在不同横向和流向间距比方案下的自由涡激振动的模拟计算,研究了组合间距比LH/D2对四圆柱振动系统的振幅频率响应、升力特性、压力特性、尾涡结构以及获取能量的影响。结果发现,合理选择横向和流向间距比可使四柱机械耦合系统从海流中获取的能量和能量密度最大化。(4)研究了交错布置五圆柱振动系统的水动力特性及能量获取效率,分析了采用交错布置的多圆柱结构规模化利用海流水动能的可行性。在四圆柱机械耦合系统的基础上,结合串列、并列和交错三种布置方式,提出了另一种由五个圆柱组成的交错布置振动系统。得到不同横向和流向间距比下该系统的响应、水动力特性、尾涡结构及获取的水动能结果。结果表明：与矩形布置的四圆柱振动系统一样,存在最优的组合间距比可使五圆柱振动系统从海流中获取能量最大,并拥有最大能量获取密度。对比两种布置形式的振动系统在其最优组合间距比时的能量获取密度值表明：采用交错布置方式明显优于矩形布置方式。此外,随着组合间距比的增加,尾涡内逐渐出现两行涡街,内侧涡街随横向间距比的增加逐渐出现“2S”模式、“S+C”模式和“2C”模式。通过对五圆柱振动结构和单圆柱结构的升力谱峰值和能量获取值分析可知,使用本文提出的多圆柱振动组合系统作为能量转换器,配合适当的驱动传输装置,对实现规模化利用海流能是有效可行性的。
[Abstract]:The demand for new clean energy instead of fossil energy is becoming more and more important in the days when non renewable energy is increasingly exhausted and environmental hazards are increasing, but the demand for new clean energy instead of fossil energy is becoming more and more important. It makes it a development field with broad prospects. The low flow current can be one of the power flow energy. The energy density is proportional to the cube of the flow velocity. If the traditional underwater turbine drive system is adopted, the hydraulic turbine is difficult to achieve effective energy conversion like a wind turbine in the current environment, based on the fluid. The driving mode of the vortex excited vibration of the flow around a cylinder becomes a choice. The vortex induced vibration uses the mechanism of the cylindrical vortex deactivation induced by the uniform flow to induce its resonance to capture the current energy, which forms a hydraulic driving system to generate electricity. It is a hydraulic driven power generation mode suitable for low speed sea current environment. This paper focuses on the study of the induced sea current environment. The parameters range of vortex excited vibration and the maximum energy of the system can be obtained, and the numerical study of vortex induced vibration is carried out by the fluid solid coupling numerical method. The optimum parameters of the vortex excited vibration to obtain the energy are analyzed. The multi cylindrical vibration system with different transverse and flow direction spacing and different layout is designed as the energy. The relationship between the vortex induced vibration response, hydrodynamic characteristics, tail vortex pattern, energy acquisition efficiency and energy density with the system parameters is analyzed in detail. The main research contents and innovation results are as follows: (1) a two way coupling numerical method which can better simulate the large vortex excited vibration is adopted. In the body region, the incompressible Reynolds time averaged RANS equation based on arbitrary Lagrange Euler (ALE) dynamic grid mechanism is described and closed by the SSTk- Omega turbulence model. The FCBI-C element model based on the ADNA system is used to calculate the discrete region of the FCBI-C element model, and the wake vortices under the large vibration of the vortex excited cylinder are realized with the corresponding algorithm. The high efficient numerical simulation of street formation has obtained the response branch, amplitude, frequency, phase angle, flow field information and the tail vortex shedding characteristics in various response branches at different reduction rates. Through literature comparison, it is proved that the analysis theory and numerical method proposed in this paper are efficient and reliable, and can be well used to simulate single cylinder or multi circle. The vortex induced vibration of the column system. (2) 4 parameters of the current energy generation based on the vortex excited vibration are proposed. The effects of the mass ratio m*, the damping ratio zeta mass damping ratio m* zeta and the water natural frequency FM, and the w on the vortex induced vibration response and energy conversion efficiency of the single cylinder are studied respectively. It is found that the mass ratio m* and the damping ratio zeta affect the energy conversion efficiency in addition to the energy conversion efficiency. It also affects the reduced speed range of effective energy acquisition, and the optimal mass damping ratio m* zeta value exists in different systems, which makes the maximum energy conversion efficiency ETA max value and the mean energy conversion efficiency maximum. It is also found that properly designing the FN and w values of the system can not only make the cylinder get the maximum energy efficiency from the flow, but also make the cylindrical structure obtain higher water kinetic energy in the wider flow velocity and reduction speed range. (3) the hydrodynamic characteristics of the four cylindrical vibration system with a rectangular spacing ratio and its energy efficiency for obtaining the ocean current are studied. In terms of the impact of the rate, and from the perspective of the scale development and utilization of the current energy, the energy converter should give priority to a system composed of multiple cylinders. This paper presents a rectangular arrangement of four cylindrical vibration systems combined with parallel and tandem configuration, and for the first time presents the dynamic characteristics of this system, which is about four. The vibration system composed of a cylinder is considered as a mass spring damping system. At any response time, the relative position of the four cylinders in the vibration system remains unchanged so that the system can obtain the best hydrodynamic characteristics. As the four cylindrical vibration system of the mechanical coupling is rectangular, the transverse and flow distance is different, the combination of the transverse and flow direction is different. Through the simulation of free vortex excited vibration of a four column mechanical coupling system under the scheme of different transverse and direction spacing ratio, the effect of the combination spacing on the amplitude frequency response, the lift characteristics, the pressure characteristics, the tail vortex structure and the energy acquisition of the four cylinder vibration system is investigated. The results are found to be reasonable. The lateral and direction spacing can maximize the energy and energy density obtained by the four column mechanical coupling system from the current. (4) the hydrodynamic characteristics and energy acquisition efficiency of the staggered five cylindrical vibration system are studied. The feasibility of using the multi cylindrical structure to scale the kinetic energy of the sea water is analyzed in the four cylinder machine. On the basis of the mechanical coupling system, an alternate arrangement vibration system composed of five cylinders is put forward in combination with tandem, parallel and interlaced three arrangements. The response, hydrodynamic characteristics, tail vortex structure and the obtained water kinetic energy results are obtained at the ratio of different transverse and direction spacing to the system. The results show that the four cylinders are arranged with the rectangular arrangement. As for the vibration system, the optimal combination spacing can make the five cylinder vibration system obtain the maximum energy from the ocean current and have the maximum energy acquisition density. The comparison of the energy acquisition density value of the vibration systems of the two arrangement forms at the optimal combination spacing shows that the interlaced arrangement is obviously superior to the rectangular arrangement. In addition, with the increase of the spacing ratio, two rows of vortex streets gradually appear in the tail vortex. The inner vortex street gradually appears "2S" mode, "S+C" mode and "2C" mode with the increase of the transverse spacing ratio. By analyzing the peak value of the lift spectrum and the energy acquisition value of the single cylinder structure and the single cylinder structure, it is known that the multi cylinder proposed in this paper is used. As an energy converter, vibration combination system is effective and feasible for large-scale utilization of ocean current energy.

【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P743

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