波浪浮标水动力特性及波浪要素识别方法研究

发布时间：2018-04-30 04:25

本文选题：可控共振式波力发电技术 + 波浪浮标　；参考：《武汉大学》2014年博士论文

【摘要】：能源是现代经济社会发展的重要物质基础和重要制约因素,并且随着经济和社会的不断发展,人类社会对能源的需求将会持续增长。因此促使人类社会不断寻求可替代并可持续发展的新能源,包括有：核能、太阳能、风能、生物燃料能和海洋能等。海洋波浪能利用技术已经成为世界各国研究的热点问题,利用波浪能进行发电具有广阔的应用前景。波力发电装置处于共振状态时提取海浪能量的效率非常高已被不同类型的波能装置试验所证实。武汉大学蔡元奇教授团队在总结200多项波力发电装置特性的基础上,提出了可控共振式波力发电技术。该技术通过实时地追踪海浪的周期、波高和波长信息,自我调整装置的特性,实现并维持装置与海浪的共振状念,从而实现了高效稳定地提取波浪能,同时该装置还具有很强的生存能力。因此,对波浪参数进行在线快速、实时、准确的测量是可控共振波力发电技术的关键技术之一本文对目前国内外波浪观测技术进行了全面总结,在综合分析了各种波浪观测技术各自优缺点的基础之上,确定了采用重力式波浪浮标进行波浪观测的方法,并开展了两个方面的研究工作：一是对波浪浮标水动力特性及随波性能的研究；另一个是利用浮标六个方向运动姿态数据进行波浪参数识别新方法的研究。研究中首先建立了一套完整的波浪浮标水动力学数值仿真平台,通过该平台易实现对各种形状波浪浮标的水动力特性及随波性能研究；其次,结合国内外浮标应用现状,设计了圆柱形及球形两种外形的波浪浮标,并利用数值仿真平台对两类外形的浮标进行了水槽摇荡自由衰减数值仿真分析,通过对摇荡自由衰减时程数据进行频谱分析,确定浮标摇荡固有频率,分析了浮标各参数对摇荡固有频率影响的一般规律并对两类外形的浮标水动力特性进行了对比研究；结合浮标在波浪力作用下的理论分析,提出了通过降低波浪频率与浮标摇荡固有频率比值的方法,以提高浮标随波性的原则,并利用数值平台进行了规则波下浮标响应的数值仿真分析,结果验证了该原则的正确性。第三,提出了一种基于浮标六自由度方向姿态数据进行波浪参数快速、实时识别的新方法。该方法建立了浮标数据出浮标动坐标系与波浪整体坐标系之间的转换关系,采用希尔伯特-黄变换(HHT)分析方法对测试数据进行分析,通过引入主成分方法(PCA)作为经验模态分解(EMD)分解的终止准则,将海浪信息分解为多个窄带过程,对窄带过程的功率分析可以得到包含波浪主要能量的本征模态(IMF)分量,该分量包含了波浪的主周期信息,通过对其进行Hilbert变换得到以某个数值期望上下波动的瞬时频率时间序列,计算其满足3仃准则的瞬时频率数学期望,得到置信度为99.74%的波浪频率值,与直接通过FFT变换得到的Fourier频率相比,该方法识别出的波浪频率具有更高精度；利用瞬时频率序列对垂直加速度进行两次积分得到波浪波面位移序列,再利用最小二乘拟合,得到主周期波浪的波高。对浮标纵摇数据进行同样的分析,可以得到波浪的波面角,进而可以计算波浪波长。同时,利用竖向加速度瞬时频率及纵摇瞬时频率标准差,可以对波浪频率显著变化进行判断。最后,采用基于微机电系统(MEMS)技术的三轴加速度计、双轴倾角计及指南针计设计制作了小型波浪浮标并进行了静水槽浮标摇荡自由衰减试验,得到了反映浮标水动力特性的摇荡固有频率；进行了浮标湖泊波浪测试试验,利用本文提出的方法分析得到的波浪的频率、波高及波长信息,结果与现场波浪实际结果较为吻合,从而验证了所提出波浪识别方法的正确性。
[Abstract]:Energy is an important material basis and important restriction factor of modern economic and social development , and with the development of economy and society , the demand of human society to energy will continue to grow . Therefore , the human society is continuously seeking alternative and sustainable development energy , including : nuclear energy , solar energy , wind energy , biofuels and ocean energy .

Ocean wave energy utilization technology has become a hot issue in the world ' s research , and the wave energy can be used for power generation . The energy efficiency of wave energy is very high , which has been proved by experiments of different types of wave energy devices .

Based on the comprehensive analysis of the advantages and disadvantages of various wave observation techniques , the method of wave observation using gravity wave buoy is established .
The other is to study the new method of wave parameter identification by using six directional motion attitude data of buoy .

In this paper , a complete set of numerical simulation platform of wave - buoy hydrodynamic numerical simulation is established , and the hydrodynamic characteristics and wave - wave performance of various wave buoys are easy to realize through the platform .

Secondly , combined with the present situation of buoy application at home and abroad , the wave buoy of both cylindrical shape and spherical shape is designed , and the numerical simulation analysis is carried out on two kinds of shapes of buoy by using numerical simulation platform .
Based on the theoretical analysis of the wave force of buoy , the method of reducing the ratio of wave frequency to floating frequency of buoy is put forward to improve the principle of wave resistance , and the numerical simulation of buoy response under regular wave is carried out by using the numerical platform , and the correctness of the principle is verified .

Thirdly , a new method is proposed for the rapid and real - time identification of wave parameters based on the attitude data of six - degree - of - freedom . The method has established the conversion relation between the buoy data and the whole coordinate system of the wave . By introducing the principal component method ( PCA ) as the termination criterion of empirical mode decomposition ( EMD ) decomposition , the wave frequency is decomposed into a plurality of narrow - band processes .
By using the instantaneous frequency sequence , the wave wave surface displacement sequence is obtained by integrating the vertical acceleration twice , and the wave height of the main period wave is obtained by using the least square fitting .

Finally , a small - scale wave buoy is designed by using a three - axis accelerometer , a double - axis inclinometer and a compass design based on the MEMS technology , and the free attenuation test of the floating buoy of the static water tank is carried out , and the oscillation natural frequency reflecting the hydrodynamic characteristics of the buoy is obtained ;
The wave test of the floating lake is carried out . The frequency , wave height and wavelength information of the waves are analyzed by the method presented in this paper . The results are consistent with the actual results of the field waves , and the correctness of the proposed method is verified .

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV139.2;P743.2

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