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Vessel-shaped fish cages are mainly composed of a large floating body, aquaculture nets and a number of steel frames. Due to the large scale of vessel-shaped fish cages, the velocity field induced by the diffraction waves and radiation waves cannot be ignored in the calculation of the loads on the net and steel frames. In turn, the loads can affect the wave-induced response of the floating body and hence the radiation waves as well as the sectional forces. In this paper, a novel method is proposed to consider the coupling effect. First, considering the irregular waves in short-term periods, the global response of the floating body is calculated in the time domain by the state-space method based on potential flow theory. Meanwhile, the velocity field considering the influence of the floating body is built according to the velocity transfer function. Then, the Morison formula is used to calculate the loads on the nets and the steel frames. Finally, the coupling achieved through numerical iterations is considered in the calculation of the twine tension, load effect of connector and the global cross-section under irregular waves. It is found that the diffraction and radiation waves make a significant difference in the twine tension and connector load effect. 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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根据某浮式生产储油船(FPSO)设计海域的环境资料,提供了短期统计特征及其长期分布律和迁航海域海况的分析计算结果,成为系泊结构物定位与环境荷载计算以及结构强度与疲劳分析的前处理模块。 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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Nuno Fonseca Carlos Guedes Soares Ricardo Pascoal 《Journal of Marine Science and Technology》2006,11(4):245-259
An analysis is presented of the vertical bending moments induced in a containership by a set of abnormal waves measured at
different locations and on different occasions. A systematic investigation was carried out by using a large set of wave traces
that included abnormal waves. In this way it was possible to assess the influence of the height, length, and shape of the
abnormal waves on the wave-induced structural loads. The probability distributions of the ship responses to the sea states
that included the abnormal waves were also calculated and were compared to the responses induced by the abnormal waves and
to fitted distributions. Finally, the structural loads induced by the abnormal waves were compared with rule values and with
long-term predictions. 相似文献
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基于RANS方程和VOF模型求解船体粘性兴波流场,开展了小水线面双体船(Small Waterplane Area Twin Hulls,SWATH)迎浪规则波中纵向运动及波浪载荷的非线性特性研究.通过数值计算结果与模型试验结果的对比分析,验证了文中方法的有效性;在此基础上,较为系统地分析了SWATH船的垂荡及纵摇运动响应、垂向加速度和波浪载荷的一阶及二阶量随入射波高的变化规律,指出SWATH船的运动响应及载荷与波高存在非线性的关系,尤其体现在响应共振区附近;相比于船体垂荡和纵摇运动,垂向加速度及波浪载荷的非线性特性更为显著. 相似文献
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To achieve rational design in waves for a submerged floating tunnel which has emerged as a new offshore transportation infrastructure, it's necessary to understand its hydrodynamic behavior. For simple but accurate estimation of hydrodynamic forces, a theoretical method is proposed and the tests with physical models in a wave flume were carried out for verification. Morison's equation was used to estimate wave loads composed of inertia force and drag force. Forces calculated by applying the linear wave theory to Morison's equation coincided well with those measured by the tests. The test results showed that mooring systems played a significant role in the movement of the submerged floating tunnel in waves. A pendulum model could be used to describe the motion of the submerged floating tunnel with a single vertical mooring. Based on the verified relations, a simple slack condition which causes the submerged floating tunnel to be unstable was also proposed. The simplified approach proposed by this study proved to be useful in designing the submerged floating tunnel in the initial stage. 相似文献
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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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全垫升气垫船对质量要求严苛,使船体浮箱结构薄弱;可两栖登陆,使浮箱破舱风险大,水密分舱只能加密。通过CATIA二次开发,实现了密集水密分舱破损计算结果的可视化,便于驾驶员基于浮箱上破口尺寸与位置,快速评估对破损进水以及船姿态的影响。CATIA气垫兴波波形的三维可视化,可直观地观察波面与气垫围线的相互关系,利于求取及理解船带漂角斜航时兴波对阻力及姿态的影响。船在波浪上航行时,随波起伏引起气垫压力波动,将外界载荷传递至船体与柔性围裙,实现气垫压力动态测试结果可视化,便于对比分析压力波动空间分布变化。 相似文献
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近年来,作用于固定式或浮式海洋结构物上的非线性波浪力正在引起广泛的注意。本文处理了规则波对固定的二维物体的二阶非线性影响,协调地求得了二阶绕射势,并进而得到了二阶定常波浪力和二阶倍频波浪力。 借助于切片理论,此方法和结果似也可用来预估船舶或某些半潜平台的二阶波浪作用力和二阶运动。 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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模型试验表明重力式网箱在波浪作用下,单纯浮架的受力贡献比例较大。本文运用波浪理论,通过建立浮架、锚绳及浮子的运动方程,采用五阶龙格-库塔进行数值求解,得到了单体网格式锚碇单纯浮架的数值计算模式。将计算模型简化为四点锚碇,并将计算结果与实验结果进行了比较,二者符合程度较好。在此基础上,比较了单体网格式锚碇与四点锚碇单纯浮架的受力,结果表明网格式锚碇方式浮架受力较小。 相似文献
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ClassNK has undertaken wide-ranging basic research covering many aspects related to the safety of ship structures, including design loads, structural analysis, strength assessment of buckling, collapse, and fatigue, and rational corrosion margins to develop new design standards which have transparency and consistency. Among the wide-ranging basic research, this article summarizes the results of extensive work on the design loads used for strength assessments of tanker and bulk carrier structures. The main aim of the research was to develop practical estimation methods of design loads with rational technical backgrounds relating to the actual loads acting on the primary structural members of tankers and bulk carriers. During this study, we proposed the following methodology. Design sea states that closely resemble the actual sea states which are considered to be the most severe for hull structures. Find practical estimation methods for the design sea states by parametric studies using the results of series calculations on representative tankers and bulk carriers. Find practical estimation methods for design regular waves which will result in the same level of stresses as those induced in irregular waves under the design sea states. We also briefly introduced some practical estimation methods for the design loads, such as ship motions, accelerations, hull-girder bending moments, and hydrodynamic pressures that are induced under design regular waves. The findings in this study have been summarized and implemented in the new design standards for tanker and bulk carrier structures.Updated from the Japanese original which won the 2003 SNAJ prize (J Soc Nav Archit Jpn 2002; 191:195–207; 2002; 191:208–220; and 2002; 192:723–733) 相似文献