共查询到18条相似文献，搜索用时 93 毫秒
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等效水深截断是混合模型试验中非常重要的一步,合理的截断方案是模型试验成功的前提。现有的研究大多忽略对平台转动的考虑,该文在静态相似准则的基础上增加对平台转动的考虑,推导了系泊系统回复力和转矩的计算公式,建立了满足静态一致性的目标函数,进而采用粒子群算法进行等效水深截断优化设计。以某深水半潜式平台为例,首先在不考虑转动的情况下对其系泊系统进行等效截断,研究发现截断水深的变化对转矩的优化结果影响较大,从而证明了平台转动是应该考虑的。其次在考虑转动的情况下对系泊系统进行等效截断,通过水动力软件验证所优化的结果,证明该方法的可行性,为后续的等效水深截断优化设计的研究提供参考。 相似文献
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进行了在规则波作用下破波带内水平混合系数测量的物理模型实验。通过在沿岸流流场中投放墨水点源和采用CCD摄像机摄像,测量了点源扩散过程。利用水深平均二维扩散方程近似解析解得到了由实验结果计算混合系数的方法。实验结果表明:扩散系数仅依赖于当地水深,与波浪参数(周期和波高)无关。沿岸流沿水深变化产生的离散作用导致顺流方向(纵向)混合系数远大于横流方向(横向)混合系数。横流方向混合系数中由波浪产生的扩散系数占总扩散系数约40%,其余为波浪破碎引起的湍流产生的扩散系数。 相似文献
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海底地形演变模型初探 总被引：3，自引：1，他引：3
当前,地理信息系统(GIS)时-空结合的分析功能还很有限,尤其是海洋地理信息系统(OGIS).由于海洋系统自身的复杂性,如海底地形这种受时-空影响的信息元素,对其预测就有相当的难度,有关这方面的文献也较少见.本文从影响海底地形演变的机理出发,结合四维空间关联性和混沌巨系统理论,提出了“空间相关混合自适应模型”.在此基础上,根据黄海辐射状沙洲西太阳沙及附近海域的具体情况,建立了该区的地形演变模型.以3个年代的测量数据为基础,运用分形内插方法生成连续多年(25a)的水深时-空数据序列,通过所建地形预测模型的处理,取得了未来年份的水深预测值,经比较检验认为是可信赖的.为江苏省东部沿海港口开发建设提供了科学依据. 相似文献
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利用温州台风网台风信息以及卫星遥感海表风场数据,研究了南海上层环流对台风的响应特征。合成分析发现,台风以Ekman输运的形式,能够诱发上层海洋十几厘米每秒的流速变化,并且主要集中在南海东部海盆。虽然台风引起的上层环流异常比较小,但是其方差非常显著。另一方面台风通过Ekman抽吸,引发上层海洋垂向运动异常,并且能够诱发强烈的等效混合。基于历史温盐数据发现,这种强的等效混合主要分布在吕宋海峡以西、越南以东以及台湾海峡,并且能够达到10~(-3)m~2/s的量级。 相似文献
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海洋环境要素计算不确定性分析 总被引：1，自引：0，他引：1
以一艘现役起重船为研究对象,对其进行不同水深(46 m和36 m),缩尺比1∶50的模型试验。采用基于二次传递函数QTF的时域准静态分析法对实际尺度起重船与系泊系统进行耦合数值分析,并与试验结果进行比较。结果表明,当水深变浅时,浅水对二阶载荷的影响是系泊力明显的主要因素,浅水对一阶载荷的影响有限。在保持系泊系统刚度线性不随水深变化的前提下进行了三个水深吃水比的数值模拟计算,结果表明,对于系泊起重船,随着水深的减小,二阶定常力有所增大;浅水对差频载荷的影响在30 m水深(吃水水深比d/h=0.27)时变得明显。对于浅水系泊系统的相关分析需要充分考虑水深对二阶慢漂运动的影响,保证系泊系统的安全。 相似文献
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用于海洋探测的多参数拖曳荧光计系统 总被引：4，自引：1，他引：3
本文论述了作者研制成功的拖曳荧光计系统。该系统的荧光传感器采用了光源调制和信号同步解调技术,同时在受光器上采用了专用遮光导水暗盒及弯曲导水管,确保荧光传感器在探测体积内水体及时交换,并能有效地消除海中太阳光的影响。系统能在任一日光强度下从海表层至８０ｍ水深任一深度,走航拖曳速度在２～１０ｋｎ内平稳地水平工作。该拖曳体内安装有荧光传感器、温度传感器、深度传感器和多路传输电子线路装置。通过一根直径为１４ｍｍ的电源／信号传输七蕊铠装电缆将拖曳体与手摇绞车及船上控制器、数据采集、记录显示器连接在一起,可以同时测量光学和水文参数,这些数据为０～５Ｖ模拟电压量输出。该系统进行了多次水池和海上现场实验及应用,达到了预期设计目标。并且借助于荧光示踪染料完成了多处海区的水体混合扩散测量实验任务,建立了实验观测方法。本文还介绍了该系统的构造、现场测量实验数据和应用 相似文献
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Optimal Design of Equivalent Water Depth Truncated Mooring System Based on Baton Pattern Simulated Annealing Algorithm简 总被引：2，自引：2，他引：0
The highest similarity degree of static characteristics including both horizontal and vertical restoring force-displacement characteristics of total mooring system, as well as the tension-displacement characteristics of the representative single mooring line between the truncated and full depth system are obtained by annealing simulation algorithm for hybrid discrete variables （ASFHDV, in short）. A“baton” optimization approach is proposed by utilizing ASFHDV. After each baton of optimization, if a few dimensional variables reach the upper or lower limit, the boundary of certain dimensional variables shall be expanded. In consideration of the experimental requirements, the length of the upper mooring line should not be smaller than 8 m, and the diameter of the anchor chain on the bottom should be larger than 0.03 m. A 100000 t turret mooring FPSO in the water depth of 304 m, with the truncated water depth being 76 m, is taken as an example of equivalent water depth truncated mooring system optimal design and calculation, and is performed to obtain the conformation parameters of the truncated mooring system. The numerical results indicate that the present truncated mooring system design is successful and effective. 相似文献
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The model test method of the FPSO and offloading system is investigated by using the development mode of “FPSO + CALM + TANKER” working in a 1700-m depth of offshore West Africa. An equivalent design based on static and dynamic similarity criteria for oil offloading line (OOL) is discussed, and a type of creative method for the equivalent design of OOL in a model test is proposed. Based on the static similarity criterion, the truncated design of the FPSO mooring system in water depth and horizontal directions is carried out. After that, a relevant static optimization is conducted. Meanwhile, to avoid interference between the FPSO mooring system and CALM mooring system, a horizontal equivalent design for the CALM mooring system is provided. On this basis, the model test scheme is conducted. Time domain coupled analyses for the whole system before and after truncation are later performed. After comparison, it is observed that the calculated results of the truncated system are basically consistent with those of the prototype system, and the design of the model test scheme is demonstrated to be robust and reliable. 相似文献
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Hybrid model testing technique is widely used in verification of a deepwater floating structure and its mooring system,but the design of the truncated mooring systems which can reproduce both static and dynamic response same as the full-depth mooring system is still a big challenge,especially for the mooting systems with large truncation.A Cell-Tress Spar operated in 1500 m water depth is verified in a wave basin with 4 m water depth.A large truncation factor arises even though a small model scale 1:100 is adopted.Computer program modules for analyzing the static and frequency domain dynamic response of mooting line are combined with multi-objective genetic algorithm NSGA-II to optimize the truncared mooting system.Considering the asymmetry of layout of mooring hnes,two different truncated mooring systems are respectively designed for both directions in which the restoring forces of the.mooting system are quite,different.Not only the static characteristics of the mooting systems are calibrated,but also the dynamic responses of the single truncated mooting line are evaluated through time domain numerical simulation and model tests.The model test results of 100-year storm in the GOM are reconstructed and extrapolated to a full depth.It is found that the experimental and numerical resuits of Spar wave frequency motion agree well,and the dynamic responses of the full-depth mooring lines are better reproduced,but the low frequency surge motion is overestimated due to the smaller mooring-induced damping.It is a feasible method adopting different truncated mooring systems for different directions in which the restoring force characteristics are quite different and cannot be simulated by one truncated mooring system.Hybrid verification of a deepwater platform in wave basin with shallow water depth is still feasible if the truncated mooring systems are properly designed,and numerical extrapolation is necessary. 相似文献
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Qiao Dong-sheng Yin Li Yan Jun Tang Wei Ning De-zhi Li Bin-bin Ou Jin-ping 《中国海洋工程》2021,35(5):700-711
The maximum predicting error of the commonly used passive truncated mooring system method may reach 30% due to the difference of dynamic characteristics between the truncated and full-depth mooring line. In this paper, the experimental strategy called three-parameter (displacement, velocity and acceleration) active control method at the truncated point of mooring line is established to implement the synchronous equivalent of motion and force, and the realization of active truncated mooring system for model test is studied theoretically. The influences of three-parameter and one-parameter (displacement) active control strategies on the compensation effects are compared by numerical study. The results show that the established three-parameter active control method can feasibly realize the static and dynamic equivalent of truncated and full-depth mooring system, laying a good foundation for the following physical model test of active truncated mooring system.
相似文献15.
Dynamic Response Analysis of the Equivalent Water Depth Truncated Point of the Catenary Mooring Line 
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下载免费PDF全文 The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedback input from the floater motions. Thus, mooring line dynamics and damping effects are artificially simulated in real time, based on a computer-based model of the problem. In consideration of the nonlinear characteristics of the sea platform catenary mooring line, the equations of the mooring line motion are formulated by using the lumped-mass method and the dynamic response of several points on the mooring line is investigated by the time and frequency domain analysis method. The dynamic response of the representative point on the mooring line is analyzed under the condition of two different corresponding upper endpoint movements namely sine wave excitation and random wave excitation. The corresponding laws of the dynamic response between the equivalent water depth truncated points at different locations and the upper endpoint are obtained, which can provide technical support for further study of the active hybrid model test. 相似文献
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Dynamics of large-truncated mooring systems coupled with a catenary moored semi-submersible 总被引：2，自引：2，他引：0
With the floating structures pushing their activities to the ultra-deep water,model tests have presented a challenge due to the limitation of the existing wave basins.Therefore,the concept of truncated mooring system is implemented to replace the full depth mooring system in the model tests,which aims to have the same dynamic responses as the full depth system.The truncated mooring system plays such a significant role that extra attention should be paid to the mooring systems with large truncation factor.Three different types of large truncation factor mooring system are being employed in the simulations,including the homogenously truncated mooring system,non-homogenously truncated mooring system and simplified truncated mooring system.A catenary moored semi-submersible operating at 1000 m water depth is presented.In addition,truncated mooring systems are proposed at the truncated water depth of 200 m.In order to explore the applicability of these truncated mooring systems,numerical simulations of the platform’s surge free decay interacting with three different styles of truncated mooring systems are studied in calm water.Furthermore,the mooring-induced damping of the truncated mooring systems is simulated in the regular wave.Finally,the platform motion responses and mooring line dynamics are simulated in irregular wave.All these simulations are implemented by employing full time domain coupled dynamic analysis,and the results are compared with those of the full depth simulations in the same cases.The results show that the mooring-induced damping plays a significant role in platform motion responses,and all truncated mooring systems are suitable for model tests with appropriate truncated mooring line diameters.However,a large diameter is needed for simplified truncated mooring lines.The suggestions are given to the selection of truncated mooring system for different situations as well as to the truncated mooring design criteria. 相似文献
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近年来,国内兴起了大力发展半潜式起重平台的势头,系泊系统的设计与优化是该类型平台开发中的关键问题之一。采用时域方法对半潜式起重平台系泊系统进行耦合动力分析,研究系泊系统主要参数对其动力响应特性的影响,并给出主要参数的设计优化流程,在此基础上,以能够满足安全校核且性能较优的系泊方案为目标,对该半潜式起重平台的系泊系统进行优化设计,并研究单根系泊缆发生破断对整个系泊系统的影响。结果表明:基于主要参数对系泊性能的影响规律,经优化设计得到的系泊方案,预留的安全欲度适中,能够保障半潜式起重平台在恶劣海况下的生存能力,同时具备较好的经济性。 相似文献
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我国的边际油田大多年产量小且开发年限短，周围没有可依托设施的油田。针对此情况，可采用“蜜蜂式”开发模式。针对浸没式可移动外输终端这一新型概念设计，选取关键工况开展了时域耦合分析，研究了系泊系统参数对可移动外输终端最大水平位移和系泊缆最大张力的影响。以可移动外输终端最大水平位移和系泊缆最大张力最小为优化目标，以系泊缆结构安全为约束条件，构建了系泊系统多目标优化模型。分别建立了基于NSGA-Ⅱ和多目标粒子群算法的系泊系统优化框架，并应用这两种算法对系泊系统进行了优化设计。结果表明，NSGA-Ⅱ和多目标粒子群算法均可以解决系泊系统多目标优化问题，粒子群算法优化速度快，但通过NSGA-Ⅱ得到的Pareto前沿优化性能更好，因此更适合开展浸没式可移动外输终端的系泊系统优化。 相似文献