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造波理论与方法研究

The Research on Theory and Method of Wave-generating Technology

【作者】 李宏伟

【导师】 庞永杰;

【作者基本信息】 哈尔滨工程大学 , 流体力学, 2013, 博士

【摘要】 在船舶与海洋工程领域内,数值模拟与模型试验是解决物体在波浪中运动及波浪与结构物相互作用问题的主要技术手段。造波是数值波浪水池计算过程以及物理水池试验过程中的一项重要技术。有效的数值造波方法不但能够提高数值波浪水池的计算效率,同时也是开发物理造波机功能的有力工具。造波机是大型水池的重要设备,其系统集成与运动控制技术是实现水池造波的基础。除造波技术外,如何消除从模型及消波装置上反射回来的波浪,避免它们撞击造波板形成二次反射波从而提高数值计算及模型试验的精度,是数值水池与物理水池都必须面对的问题。本文针对数值造波方法、多向造波机的系统集成与运动控制、水池造波的实现以及主动吸收造波技术进行了研究,主要内容包括:(1)基于CFD技术建立了粘性数值造波模型,采用速度边界造波方法对三维水池中二阶Stokes波的生成进行了模拟,采用质量源造波方法对孤立波的生成进行了模拟;应用混合欧拉拉格朗日自由面条件建立了基于高阶边界元法的势流数值造波模型,结合波谱相位聚焦的原理,应用该模型对摇板式造波机生成聚焦波进行了仿物理造波模拟。(2)通过对进口伺服产品进行技术解读,基于Sercos总线协议建立了多向造波机的控制系统,编写了伺服驱动器中的位置控制程序、伺服控制器中的插补程序及上位机中的造波软件,实现了多向造波机的运动控制,通过正向规则波造波过程中多点同步测试,对多板同步控制进行了验证。(3)基于不规则波的线性叠加法,讨论了海洋工程模型试验中先进的白噪声不规则波的生成方法,并在水池中进行了白噪声不规则波模拟试验;讨论了单边摇板式多向造波机生成斜向波与三维波的方法,并基于多向造波机的差动控制在水池中进行了模拟试验,编写了频谱分析及方向谱分析程序,通过频谱分析与迭代修正在水池中生成了较好品质的斜向规则波、斜向不规则波及三维波。(4)基于势流理论与线性叠加原理,对主动吸收造波原理进行了推导,通过理论推导将目前两种主流的主动吸收造波技术统一在一个理论框架内;从控制系统的角度诠释了主动吸收造波技术,从而将智能控制的思想引入主动吸收造波问题,提出一种新颖的主动吸收造波策略。(5)从数值仿真与物理水槽试验两个方面对本文提出的主动吸收造波方法进行了验证。在数值水池中,分别对前人方法与本文方法进行了主动吸收造波对比研究;在物理水槽方面,建立了摇板式主动吸收造波原理样机,针对主动吸收造波机运动的特点,编写伺服电机实时插补位置控制程序,实现了造波机目标行程的在线修改,并基于入、反射波浪分离的时域算法,对主动吸收造波的吸波效果进行了分析与评价。

【Abstract】 In the field of naval architecture and ocean engineering, numerical simulation and modeltest are two main approaches to investigate the wave-structure interaction problems. Wavegenerating is the key aspect of the numerical wave tank technique and also the correspondingphysical basin. Effective numerical wave generating method could improve the efficiency ofthe numerical wave tank, which in turn is beneficial for researching the wave generatingprocess in the real physical world as well. Wave-maker is one of the fundamental equipmentsfor ocean basin, and the system integration and control strategy are the indispensable basis forgenerating high quality waves. Besides wave generating, active absorbing the wave reflectedby the model and beach also matters a lot for both the numerical and physical tank. Otherwise,this part of the wave would again be pushed away by the wave-maker towards to the model,which is also referred as second reflection. Obviously, this additional reflection will inevitablycorrupt the accuracy of the test. This thesis concerns on the following issues: numerical wavegenerating; the system integration and motion control of multi-directional wave maker; activewave absorption. The detailed illustration is as follows:(1) Viscous numerical wave tank was established based on CFD theory, by which3Dsecond order stokes wave and solitary wave were simulated using velocity boundarytechnique and mass source techniques respectively. Highly non-linear boundaryelement method coupled with Mixed-Euler-Lagrange method were employed todevelop the numerical wave tank. Based on this model and using the phase focusingtheory, the focus wave phenomenon was simulated through flap-type wave maker.(2) Based on the analysis of the imported control server, the control system of themulti-directional wave maker was set up by Sercos bus. Moreover, the position controland interpolation programs were developed as well. Through all these fundamentalwork, the accurate motion control was realized. The Synchronous Control ofmulti-wave-maker was achieved by synchronal testing of the regular wave during thewave making process.(3) According to linear superposition theory, the advanced white noise irregular wavegenerating technique was investigated and conducted in the wave basin. The generation of oblique wave and short crest wave by unilateral rock-flap multi-directionalwave-maker were investigated and the physical test was also conducted in the wavebasin by differentiating control of wave-maker. Frequency and directional spectrumanalysis programs were developed. Through spectral analysis and iteration amendment,high quality oblique regular, oblique irregular and shor crest wave were obtained in thebasin.(4) Through potential and linear superposition theories, the principle of active waveabsorption was investigated. The two mainstream theoretical models were integrated ina single framework. The active wave absorption technique was re-interpreted throughthe angle of modern control theory. As a consequence, the intelligent control wasintroduced and a new control strategy was proposed as well.(5) The new active wave absorption theory was verified by both numerical and physicalsimulations. Specifically, in the numerical wave flume, the proposed method andprevious one were comparatively studied; For physical situation, the flap-typeprototype was established. According to the distinguished features of active waveabsorption wave-maker, the real time position compensation control system wasdeveloped and online modification of trace of the rocker was realized, and theperformance was assessed by the reflection separation algorithm.

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