【作者】 郝双户；

【导师】 董国海； 宗智；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2008， 博士

【摘要】 随着世界人口的不断增长,人们对水产品的需求快速增加,而且海岸线附近的人类活动日益频繁,使得浅水养殖变得非常困难,再加上浅水养殖过程中带来了严重的环境污染,所以迫使水产养殖不得不延伸到深海进行。这主要因为深水区域的人类活动较少,而且那里有较高质量的海水,有利于鱼类生长,另外深水对于网箱的残渣也有较高的处理能力。作为一种重要的深水养殖工具,深水网箱正在越来越多的被投入到实际生产中,目前应用较为广泛的是深水重力式网箱。浮架作为重力式网箱的主要受力构件,不仅承受了波浪力等的作用,而且还是网箱的工作平台,它的安全直接关系到整个网箱系统的功能能否实现。所以,本文重点研究重力式网箱的浮架系统的水弹性响应,即分析浮架的运动和变形的流固耦合问题。论文包括以下几个部分:首先,在绪论中介绍深水养殖网箱的背景以及相关学科的研究现状;第二章建立浮架数学模型,根据刚体运动学原理,建立浮架的运动方程;第三章运用曲梁理论,建立了圆环的平面内和平面外变形的控制方程;针对上面两部分所得控制方程,由于计算圆环所受波浪力采用了莫里森方程,而在莫里森方程中包括了圆环的运动,所以运动方程和变形方程就需要耦合求解,第四章便给出了计算所用到的解耦方程;在分析浮架的水弹性前,需要对所得方程的实用性进行验证,第五章将浮架横荡和升沉的计算结果与物理模型实验的测量结果进行对比,得到较好的相关性,另外还考虑在圆环上加载集中力,包括平面内和平面外加载,通过对比商业软件ANSYS的计算结果,发现两者很好的吻合,这验证了本文计算圆环变形的控制方程;第六章即运用所得到的耦合方程讨论浮架的水弹性问题,探讨了几个因素对圆环变形和运动的影响,包括波浪入射角、锚绳布置角度、浮架尺度和波浪周期等,另外对于一些危险情况文中也做了说明。最后对本文的成果进行总结,并对今后的工作进行了展望。更多还原

【Abstract】 The demands of fishery products are growing up with the increasing world population. And the people frequently enjoy themselves in the offshore.Then the development of the offshore aquaculture is faced with stagnation.It is unallowable that the offshore farming brings serious pollution.Therefore the aquaculture must be put into the open sea because of high quality of water,few recreations and high efficiency for the draff in the open ocean. Open ocean aquaculture has been put in schedule,and open ocean fish cage is becoming an important technique.The flotation ring is a primary loading-bearing component of a gravity-type fish cage,which supports the whole fish cage.Its safety is closely related to the feasibility of fish cage.And large deformations of a flotation ring have been observed in the field scale.Therefore it is necessary to study the hydroelasticity of the flotation ring.The aim of the dissertation is to analyze the elastic deformation of a circular ring subjected to water waves,coupled with its rigid-body motions.There are seven parts in the dissertation.Firstly,the author introduces the background and development of the deep-water fish cage.Secondly,the numerical model of a flotation ring is proposed,and the equations governing its six degrees of freedom motions are built up according to the theory of rigid body kinemics.In the third chapter the deformation equations of the ring are given by virtue of the curved beam theory.The in-plane and out-of-plane deformations of the ring are represented according to the modal superposition method,and they are applied to the governing equations.Then it becomes easy to solve the governing equations.For the cross-sectional diameter of the ring is much less than wave length,the wave forces are presented by Morison fomula.Because the acceleration of the ring is included in Morison’s formula,the deformation equations of the ring are coupled with its motion equations.Then it is necessary to validate the above governing equations before they are used to solve the hydroelasticity of the ring.In the fifth chapter the good correlation of the maximum positive displacements for the surge and heave of the ring is obtained through the comparison between the predicted results and model experimental data.The shape of the out-of-plane and in-plane deformed ring predicted from the numerical method agrees well with the results from the commercial software ANSYS.So the numerical method is feasible to analyze the elastic deformations of the ring subjected to water waves.And then some discussions of hydroelasticity of the ring are carried out,including the effect of the wave direction,the configuration of mooring cables and the dimension of the ring.Also the responses of the deformations and motions of the ring with wave period are considered.For the further realization the deformations,motions and mooring cable forces are analyzes under the poor wave conditions.Finally the conclusion is given,and prospects of open ocean fish cage are discussed.更多还原