Topside Axial Bearing Wear Under the Eccentric Load of a Single-Anchor Leg Mooring System in Bohai Bay

Because the applications of single-anchor leg mooring yoke systems(SYSs)are rarely studied in the offshore industry,the design of such systems features some uncertainties.This paper investigated the effect of eccentricity on the wear of the topside axial bearing of a SYS.The eccentricity of the topside was verified by on-site inspection,and the axial bearing wear was found to be far more serious than the original design.The contact status between the axial bearing and flange surface was studied on the basis of the actual topside load by using nonlinear finite element analysis.Wear tests of the topside bearing under uniform and eccentric loads were also performed to study the effect of eccentric loads on the wear rate.The key parameters obtained from numerical simulations and experimentation were used to calculate the wear depth via a simplified linear wear model based on the product of the pressure and sliding distance.Results showed that eccentric loads are the main factor responsible for the excessive wear of topside axial bearings.

A Single Mooring System with Sag-Extensibility and Flexural Rigidity Applied to Offshore Platform

Floating platform system has been extensively used in ocean exploitation, particularly for a tension-leg platform （TLP） system in deep water. Most of the TLPs are multi-mooring systems, where multi-joints are connected to the tension-legs so that the platform is not allowed to twist freely and may subject to enormous force induced by large incident waves in the weak-direction of the structure. This study aims to exploit a single moored offshore platform system that may attract less force and can be operated with less effort. In our analysis, in addition to mechanical properties of the tether, two important properties are also taken into consideration for the single mooring tether with expanded cross sectional dimension and utilization of stronger material, namely, the sag-extensibility and the flexural rigidity. Finally, the dynamic structural behavior produced by the mechanical effects on the new system is investigated and compared with that of traditional design while the wave-structure interactions of large body are also accounted for. Our study finds that the neglect of sag-extensibility or the flexural rigidity of large, strong mooring cable may result in a conservative but not necessarily safe design.

Performance of Two Types of Mooring Systems in the Heave Motion of a Two-body Floating Wave Energy Converter

This work investigated the influence of two types of mooring systems on the hydrodynamic performance of a two-body floating wave energy converter(WEC). It also investigated the effects of the physical parameters of the mooring system on the amount of extractable power from incident waves in the frequency domain. The modeled converter comprised a floating body(a buoy), a submerged body with two mooring systems, and a coupling system for two bodies. The coupling system was a simplified power take-off system that was modeled by a linear spring-damper model. The tension leg mooring system could drastically affect the heave motion of the submerged body of the model and increase relative displacement between the two bodies. The effects of the stiffness parameter of the mooring system on power absorption exceeded those of the pretension tendon force.

Evaluation of the Safe and Failure Zones of Mooring and Riser Systems in a CALM Oil Terminal

The mooring and riser system is the most critical part of an ofshore oil terminal.Traditionally,these two parts are designed separately without considering the nonlinear interaction between them.Thus,the present paper aims to develop an inte-grated design process for riser systems with a lazy-S confguration and mooring systems in the ofshore catenary anchor leg mooring(CALM)oil terminal.One of the important criteria considered in this integrated design is the ofset diagram and safe operation zone(SAFOP)related to the mooring system and the riser,respectively.These two diagrams are obtained separately by diferent analyses;therefore,codes or standards are available separately for two components.In this methodol-ogy,the diagrams of both risers and mooring lines are incorporated into a single spiral,thus identifying the safe and failure zones of risers and the mooring lines of the oil terminal.This,in turn,leads to substantial benefts in terms of overall system response,cost reduction,and safety to the ofshore oil terminal.To implement this process,three diferent riser lengths with the lazy-S confguration are considered at three diferent sea depths at the terminal installation site.For each condition,the integrated design of the mooring system and riser is executed according to the derived procedure.Then,coupled dynamic models,wherein both buoys and hoses are included,are developed using OrcaFlex.Results show that the criteria of the relevant regulations are not satisfed by reducing the length of the riser relative to the designed size.Further,as water depth increases,this type of riser confguration shows good coupled performance while interacting with the mooring system.In the cross ofset mode,the maximum margin is created between the ofset diagram and the SAFOP diagram,while the most critical dynamic response of the tanker and terminal system occurs in the near and far modes.Therefore,with this method,the best position for the riser direction with the tanker direction is 90°in the best case.

锚系作业船在超深水锚腿预铺设中的应用实践

海上浮式生产设施通常采用多条系泊锚腿将上部平台设施与海底锚桩连接,水深超过1500m时锚腿的预铺设工作面临前所未有的挑战和困难。本文结合中国南海西部半潜式平台系泊锚腿预铺设作业的工程实践,以动力定位系统、主动深沉补偿式折臂吊机、500t锚系处理绞车配合作业的方法下放锚腿;结合锚头链与锚桩连接、锚腿中段聚酯缆下放、锚腿湿存等问题,深入分析、探讨、总结锚系作业船舶在施工中的要点和难点。

考虑桩基错动的深水张力腿平台动力响应研究

由于地震、断层、滑坡和沉降等原因,张力腿平台(tension leg platform, TLP)下端的桩基可能发生错动。考虑平台本体有限位移、六自由度运动耦合、瞬时位置和瞬时湿表面、自由表面效应等非线性因素,建立TLP系统的耦合动力学方程。采用变步长龙格库塔算法编写了数值计算程序,得到了波浪作用下平台本体六个自由度运动响应和系泊张力响应。通过文献对比,验证了理论模型和计算程序的正确性。基于南海流花油田一年一遇的设计工况,计算得到桩基下沉0.1 m时16个工况下平台系统的动力响应的时间历程。以正常工况为基准,对比了不同工况中平台本体六个自由度运动、系泊张力的幅值和标准差,研究结果表明:桩基下沉对平台的六自由度响应和张力腿张力幅值产生明显的影响,但不加剧运动响应和张力响应的波动;桩基下沉会破坏平台系统原有的对称性,引起垂荡位移的较大恶化;桩基下沉会引起张力腿张力大幅增大,存在张力腿断裂和系泊失效的风险。

海上风电机组浮式基础结构综述

随着中国对可再生清洁能源需求的逐步增加,近海风电能源的开发将逐渐趋于饱和,海上风电走向远海、深海区域是必然趋势。浮式基础结构的研发和工程应用,是推进海上风电向远海、深海区域发展的关键技术措施。对海上风电机组浮式基础结构的适用水深范围、基本形式、系泊系统、制作与安装进行全面综述,旨在为中国发展远海、深海风电提供技术参考。

张力腿平台系泊系统敏感性分析

张力腿平台是一种典型的深水采油平台,其优良的运动性能得到了业内的认可。针对一座传统式张力腿平台进行了数值模拟和分析,得到平台的动态响应。对极端工况下平台筋腱不同的刚度、布置角度、预张力和筋腱数目进行了计算和对比,得到了系泊筋腱受力以及平台位移的时历曲线。通过数据的分析得到了一些在实际工程应用中有用的结论。

随机波浪中张力腿平台耦合运动及系泊系统特性研究

张力腿平台(TLP)是一种垂直系泊的半顺应半刚度式平台,预报平台的运动响应及锚泊系统的张力是张力腿平台结构设计的重要基础。应用挪威船级社SESAM软件在频域和时域内研究了张力腿平台在随机波浪中的非线性运动响应及系泊系统特性,并在试验室中通过缩尺比为1∶40的模型进行了试验验证。在试验验证的基础上,将仅考虑浪与考虑浪、流联合作用下的张力腿的张力平均值、幅值及标准差作了对比。结果表明,在较低海况时,考虑浪和流时的张力腿与不考虑流的情况变化不大;在较大海况时,流的影响不可忽略,考虑流的张力腿变化幅度要略大于不考虑流的情况。

冲击载荷作用下张力腿平台瞬态动力响应及系泊特性研究

瞬态冲击荷载作用下平台主体产生大幅运动,易引起系泊系统断裂,危害平台安全。采用数值分析的方法对脉冲荷载作用下张力腿平台主体与系泊系统的耦合动力响应及系泊特性开展了研究。考虑正弦脉冲、三角脉冲及矩形脉冲等典型冲击荷载的影响,借助自编程序对运动微分方程进行了数值求解。重点考察非线性阻尼、脉冲形式、碰撞部位、撞击角度等诸因素对平台瞬态动力特性的影响。研究发现:三种典型脉冲作用下,计及非线性阻尼的纵荡及纵摇响应幅值均小于不考虑非线性阻尼时的计算结果;脉冲峰值影响平台运动响应的幅值;保持相同脉冲冲量时,三种脉冲形式作用下平台时间历程曲线基本一致;碰撞部位及撞击角度对平台动力响应均有较大的影响。

新型海上浮式风力机概念设计

以美国可再生能源实验室(NREL)研究所选用的5MW海上风力机为主要参考模型,概念性地提出一种新型张力腿-锚缆结合式系泊系统的浮式平台形式。综合考虑顶部风机响应、支撑结构和下部系泊系统的动力耦合作用,参照IEC 61400-3海上风力机设计规范中的典型设计工况,采用数值模拟的手段对新型海上风力机浮式平台进行风浪流联合作用下的时域分析。结果表明,新型张力腿-锚缆结合式系泊系统可很好地保障海上5MW浮式风力机的正常工作性能,其对未来海上浮式风力机的发展具有积极的指导意义。

单锚腿系泊系统动力响应的时域计算方法

在时域内建立了单锚腿系泊系统在风、浪、流联合作用下动力响应的计算方法。在分析波浪荷载时,使用了设计波法和非线性Stokes五阶波,并由经验公式求出了船舶的风、流荷载作用力。系统的动力初始条件由准静态方法求得。由静态方法得到系泊力后,使用了四阶Runge Kutta方法求解船舶的运动时历,并作为立管和浮筒动力计算的边界条件。由二维梁柱单元和集中质量法构建了立管和浮筒的数学模型,立管的运动方程用Wilson θ法求解。模拟计算结果和试验结果进行了比较,吻合得较好,表明本方法能够用于计算单锚腿系泊系统的动力响应。

基于吸盘负压吸附的六足爬墙机器人关节转矩优化分配

针对采用吸盘负压吸附的六足爬墙机器人在多种运动模式下的关节转矩分配问题,提出基于总能耗目标优化的转矩分配方法。在确定吸盘翻转力矩约束、实现关节转矩与足底接触力转换的基础上,推导机器人动力学模型,进而用Moor-Penrose逆矩阵法和简体爬山算法求解总能耗最优目标下的机器人总功率与机器人各运动模式下各位姿(表现为各关节转角)之间的关系。该方法能有效适应爬墙机器人的多种运动模式,提高了机器人的环境适应能力。实验样机仿真结果表明,所提出的算法简单有效、实现方便,并且能有效确定站立模式最小总能耗位姿,以及在设定的侧立安全指标范围内的侧立最安全位姿。

CALM单点管道设计综述

通过对CALM单点系泊系统上的管道设计思路及原则进行论述,介绍了管道设计中需要考虑的重要因素、设计原则、规范和工况设定等,归纳了整个设计流程中的关键点,为类似设计提供了指导和设计依据。

深水网箱的单锚腿系泊系统动力特性分析研究

随着网箱养殖的快速并且向深远海发展,传统的辐射式多点系泊方式的应用受到限制。论文在软钢臂的特点上设计出一种适用于网箱系泊的单锚腿系泊系统,依据三维势流理论得到浮筒的水动力系数为基础,求解了系泊系统的刚度,完成了海域实测与数据验证;其次,在时域范围内建立了系泊系统与网箱的动力分析模型,计算了极端海况、多组合情况下锚泊线顶端激励、浮筒与底部重量的运动响应,并对相互间影响关系进行了分析。研究结果对养殖网箱新型系泊系统的设计提供了一种思路。

超深水环境下新概念张力系泊式水中生产平台准静态稳性特性研究(第二部分)

本文聚焦于一种新概念张力系泊式水中生产平台(STLP),该平台可在超深水环境下应用浅水完井设备和技术开发大型油气田。重点研究STLP准静态稳性设计评估分析模型的建立,STLP的准静态稳性将确保STLP具有良好的技术性能和较高的安全性。STLP准静态稳性的实现是通过将人工海床定位于海平面以下一定位置,以使表面波浪载荷最小化。首先提出STLP准静态稳性研究的分析理论和数值模拟方法;接着,研究不同系泊方式对STLP稳定性的影响;之后,研究极端风暴条件下,系泊缆绳失效对STLP破损稳性的影响;最后进行总结和讨论。结果表明,对于3000 m以上的深海,STLP是一种可行的、具有竞争力的深海油田开发方案。

CALM单点系泊系统浮筒主轴承选型研究

目前我国单点系泊系统的研究尚处于初级阶段,对于CALM型单点浮筒主轴承的研究较少。为此,研究了CALM单点系泊系统浮筒主轴承的选型设计方法。参考大型回转轴承的相关标准规范,结合海洋环境和CALM浮筒的使用特点,对CALM单点系泊系统浮筒主轴承的选型进行了分析研究。探讨了浮筒主轴承的类型选择、尺寸确定、材料选择、密封设计、加工精度要求和检验试验要求的确定方法和依据。CALM单点浮筒主轴承选型时应综合考虑环境条件、工况特点和浮筒结构等诸多因素。海上环境相对恶劣,应该对安全系数、主体材料和密封方案进行特殊考虑,使之满足海洋环境的要求。该技术的研究和掌握对突破国外技术垄断,推进单点系泊系统在我国的推广应用具有重要意义。

CALM单点系泊系统设计综述

介绍了悬链锚腿系泊(CALM)单点系泊系统设计中需要考虑的重要因素,如船型和货运量核算、单点选址原则、工况设定、设计衡准、鱼尾运动解决方案等。归纳了整个设计流程中的关键点,讨论了如何确保单点系泊设计的安全性。

张力腿平台码头舾装阶段系泊系统设计

研究张力腿平台(Tension Leg Platform,TLP)码头舾装阶段系泊系统设计的关键技术,包括:系泊方案的设计要点、系泊环境载荷的计算方法、系泊力的时域计算和系泊应急预案准备等。以一艘深水TLP在L型码头的系泊为例,详细介绍TLP的系泊技术,提出一套切实可行的系泊方案。研究成果可为TLP建造提供参考。

悬链系泊系统中的粘接软管

悬链系泊(CALM)系统中的粘接软管是主要的装卸油设施。此类软管主要材质为橡胶材料,通过铺放涂胶织物、缠绕钢丝等加强层,增加其拉伸和弯曲强度。目前,国内海洋工程中对粘接软管的研究和应用较少。通过对CALM系统中两种粘接软管即漂浮软管和水下软管的结构选型、长度和布置形态的研究,提出了软管的结构选型和布置形态的设计方法。最后以水下软管为例进行了静态和动态分析。