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采用三维势流理论计算不规则波中的两浮箱的运动响应,其中考虑了它们之间相互作用的影响。而后计算出两模块上连接器之间的相对运动,最终找到浮箱拼装的最佳状态。并提出了一种有效而又简单的方法预报两浮箱在波浪中的耦合运动,为浮箱的拼装作业提供了依据。 相似文献
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XU Li ZHANG Min WANG Yan-ying 《船舶与海洋工程学报》2007,6(3):6-11
Mathematical models simulating steep waves at a focus point are presented in this paper. Simulations of extreme waves in a model basin were used to determine the loads on floating structures induced by the waves. Based on a new wave theory, numerical test results show that the simulation procedure is effective and the induced motion of water particles in the front of waves is an important factor influencing impact loads on floating bodies. 相似文献
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In this paper, we present a numerical study on the hydroelastic response of a 4.6 km long fjord crossing floating bridge subjected to wave loads. The bridge is straight in design and supported by 35 pontoons along its full length. To limit the response to horizontal loads, four clusters of deep water mooring lines are engaged to increase the transverse stiffness of the bridge. Owing to the very large span across the fjord, inhomogeneity in the wave field exists. This study examines the various effects of inhomogeneous wave loads on the dynamic responses of the floating bridge. These include the spatial variations of the wave direction, significant wave height and peak period as well as the coherence and correlation of waves along the entire length of the floating bridge. For the purpose of comparison, the dynamic bridge responses under homogeneous wave load cases are also studied. In addition, the effects of wave load components and short-crestedness are presented and discussed. 相似文献
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文章基于三维时域势流理论和弹性细长杆理论,研究并提出了深海系泊浮体物面非线性时域耦合动力分析方法。该方法采用时域物面非线性理论方法在瞬态位置直接时域模拟系泊浮体所需水动力,结合有限元方法计算系泊缆索的动力响应,利用异步耦合方法实现浮体和系泊缆索的时域耦合动力求解。既满足系泊浮体时域水动力耦合,又满足系泊浮体和系泊缆索动力耦合。通过对二阶非线性不规则波作用下深海系泊半潜式平台的时域耦合响应特性进行研究,将不同海况下物面非线性时域耦合静力响应和动力响应与间接时域耦合动力响应的三种方法计算结果进行比较。研究结果表明,系泊缆索动力响应明显,平台瞬态空间位置对垂荡低频运动影响较大,有必要在平台瞬时湿表面采用动力响应方法进行深海系泊浮体时域耦合响应分析。 相似文献
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Our aim is to investigate the behavior of submerged supple nets. This work generates many problems owing to the discontinuous
and highly flexible nature of the nets. Only the action of external forces can bring an infinitely flexible structure like
a net into a definite shape. When considering supple nets immersed in a fluid, these external forces themselves depend on
the net geometry. A numerical method to solve this fluid-structure coupling problem is proposed, and is applied to fish farms.
In order to validate the calculation model of the hydrodynamic forces on the mesh sides, we measured the hydrodynamic forces
on a plane panel of netting spread across a transverse current. We thus proved that the Landweber model modified according
to the Richtmeyer formula as regards friction gives good results. The calculated shape of the fixed net cage is qualitatively
in accordance with flume tank observations. We have adapted the algorithm to the study of the dynamic behavior of floating
fish farms. 相似文献
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通过试验研究了不规则波浪在一陡坡(1:10)上的传播过程中的非线性特征。为达到研究目的,在试验水槽中以JONSWAP谱为靶谱生成了两组随机波浪。试验结果显示,在坡前常水深区域和坡顶,两种波况下波高分布均符合瑞利分布;但是在变浅区域两种波况的波高分布却不尽相同。应用基于小波变换的二阶相位谱来分析波浪在传播过程中的非线性相位耦合特征,结果表明:随着水深的变浅,波浪的非线性逐渐增强并且参与非线性相互耦合的频率成份也越来越多。通过二阶相位谱发现:随着水深的减小,参与最强的非线性相位耦合频率向高频处移动。另外通过傅立叶频谱、二阶谱以及二阶频谱共同分析陡坡上两组波况下低频波浪的演化情况。 相似文献
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《Marine Structures》2004,17(6):435-454
The hydroelasticity of a very large floating plate with large deflections in multidirectional irregular waves is discussed. After a brief introduction on wave loads on a flexible structure, the paper derives the generalised fluid force acting on a floating structure in multidirectional irregular waves. The nonlinear sectional forces induced by the membrane forces in the plate are deduced. The hydroelastic response equations of a floating plate with large deflections in multidirectional irregular waves are established, and a solution method in the frequency domain is discussed including extreme value statistics. A very large floating structure is chosen as an example. The numerical results show that the influence of the membrane forces on the vertical displacements and the bending moments is noticeable but not that large. 相似文献
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精确评估模块连接处荷载特性对超大型浮体的水动力设计及结构安全性研究具有重要的工程意义。文章以5模块半潜式超大型浮体为研究对象,考虑碰撞荷载和风、浪、流环境荷载的联合作用并采用AQWA软件对超大型浮体模块连接点处的受力特性开展了数值计算。船舶碰撞荷载简化为矩形脉冲,采用定常风、定常流以及JONSWAP波谱,探讨了船舶碰撞角度、撞击位置、环境荷载等因素对模块连接点受力特性的影响。该文的研究成果可为事故荷载作用时超大型浮体连接器结构设计和强度计算提供一定依据。 相似文献
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《Marine Structures》2007,20(1-2):71-99
Based on the dynamical theories of water waves and Mindlin plates, the investigation of the wave-induced responses and the vibration reduction of an elastic floating plate in water waves are presented by using the Wiener–Hopf technique. Firstly, without regard for the case of elastic connector, the calculated results obtained by the present method are in good agreement with the results from the literature and the experimental results. Therefore, it can be shown that the present method is valid. Secondly, the relations between the spring stiffness and the parameters of wave-induced responses of floating plates, which is used to connect the sea bottom and the floating plate's edge, are analyzed by the present method. Therefore, these results can be used as theoretical bases at the design stage of super floating platform systems. 相似文献
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An innovative offshore system integrating a floating offshore wind turbine with a steel fish farming cage (FOWT-SFFC) has recently been developed by the two leading authors for offshore wind and aquaculture industry. The purpose of this paper is to investigate the dynamic responses of FOWT-SFFC subjected to simultaneous wind and wave actions in the harsh South China Sea environment by a series of model tests. The tests are conducted at the Tsinghua Ocean Engineering Basin with Froude scale of 1:30. In this paper, the similarity law and setup of model tests are given first. Then a series of calibration tests and identification tests are carried out to validate the capacity of wind generator and wave maker, and to identify the vibration frequencies of tower, the stiffness of mooring system, natural periods and system damping, motion response amplitude operators (RAOs) of FOWT-SFFC, and thrust-speed performance of the turbine in wave basin. After that, seakeeping tests are implemented for random waves, followed by a sequence of load cases including normal operating and extreme conditions. Constant wind speeds and random wind speeds are respectively considered in load combinations. The experimental results affirm the excellent seakeeping and dynamic performance of FOWT-SFFC. Existence of metal fish nets increases the damping of foundation's 6 degree-of-freedoms motions. Generally, the influence of nets on the dynamic responses is insignificant in wind sea states. 相似文献
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深水SPAR风机系统全耦合动力响应分析研究 总被引:1,自引:0,他引:1
文章采用联合开发的计算程序对深水SPAR风机的浮体、锚泊和风机各子系统进行了水—气动力的全耦合数值分析,研究了深水浮式风机系统的动力响应特点。浮体水动力计算采用基于二阶精度的混合波浪模型(Hybrid Wave Model)的MORISON公式,锚泊系统采用细长杆理论通过非线性有限元方法实现,风机系统的空气动力分析采用基于多体气动弹性理论的FAST模块。以浮体控制方程为主体,通过模块间的载荷与位移传递在每个时间步上迭代求解,形成完全耦合的时域分析方法。通过对NREL的5MW SPAR风机系统在随机海况下的水动力响应分析,验证了该方法的有效性,并分析了浮式风机子系统间的混合动力作用。 相似文献
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精确评估模块柔性连接性能对连接器和超大型浮体的结构安全性具有重要意义,而模型试验是获取超大型浮体模块柔性连接性能的必要手段。文章以横向浮筒式的浅吃水超大型浮体为研究对象,根据连接器动响应计算结果,设计了柔性连接器模型;通过不同幅值和载荷组合的连接器静态拉伸和压缩试验,研究了超大型浮体连接器的刚度特性,探讨了组合载荷对连接器刚度的影响;通过不同幅值和周期的连接器纵向动态载荷试验,研究了超大型浮体连接器在动态载荷作用下的结构响应,验证了超大型浮体连接器结构的安全性和适用性。试验结果表明在静态和动态载荷作用下文中设计的柔性连接器连接可靠、结构安全,连接器载荷、位移和应力测量结果可为验证连接器结构设计和计算方法提供依据。 相似文献
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Takashi Tsubogo 《Journal of Marine Science and Technology》1999,4(2):76-83
This paper deals with the dispersion relation of hydroelastic waves in pontoon-type very large floating structures (VLFS)
using a simple beam modeling, where the term hydroelastic waves means propagation of deflection vibrations in VLFS. The purpose of this paper is to show the properties of the hydroelastic
waves. The dispersion relation of hydroelastic waves propagating in an infinite plate floating on the water is derived based
on the linear water wave theory. The effects of the water depth and of the bending rigidity of the floating plate on the wavelength,
phase velocity, and group velocity of the hydroelastic waves are shown theoretically or numerically. Then, the dispersion
relation of hydroelastic waves in a finite plate floating on shallow water is investigated. It is shown that the wavelength
or the phase velocity of the hydroelastic waves varies with the location in the plate.
Received for publication on April 7, 1999; accepted on Aug. 20, 1999 相似文献