缆绳预张力和刚度对自升式平台码头系泊性能的影响

在台风等恶劣环境下,自升式平台在码头进行舾装、维修作业时极易发生碰撞事故,需要对其进行码头系泊。系泊方案一般采用中间垫靠驳船的方式。本文利用流体软件Fine/Marine计算平台的风、流载荷系数,结合系泊软件Orcaflex模拟了在台风状态下自升式平台码头系泊系统,通过给缆绳设置不同预张力和刚度,计算分析最终系泊缆绳受力和平台运动。结果显示施加预张力和增加缆绳刚度均能减小缆绳最终受力和平台运动幅度,而且增加刚度的效果好于增加预张力;每根缆绳预张力大小还应保证一致,更有利于系泊系统稳定性。所得结论对于自升式平台码头系泊方案设定具有重要意义。     

采用弦式系泊系统的海洋平台水动力性能数值模拟分析北大核心CSCD

[目的]弦式系泊系统是针对特种海洋平台的永久靠泊需求而提出,需要研究采用该系统的平台的水动力性能,以验证其对永久靠泊需求的适应性。[方法]首先,基于三维势流理论,采用边界元方法建立码头靠泊平台数值模型,并对不同码头潮位条件下的系泊平台进行频域数值模拟;然后,在时域模拟中引入弦式系泊和传统码头缆绳系泊2种不同的系泊系统,模拟系泊平台在极端波浪作用下的表现,参数化分析码头潮位对系泊平台运动响应的影响。[结果]结果显示,弦式系泊系统通过提供全方向的回复力,加强了平台转动运动限制,大幅削弱了系泊平台的横摇运动,能将环境载荷能量转移到平动运动,进而加强了对平台整体运动的限制;系泊平台的运动范围均衡且稳定可控;该系统对平台的运动限制效果受码头潮位变化影响小。[结论]研究表明弦式系泊系统相较于传统码头缆绳系泊更适应特种海洋平台的永久靠泊需求。     

台风条件下自升式平台码头系泊缆绳破断分析

考虑到在码头舾装期间,自升式平台由于尚未实施插桩,当遇到超强台风天气时,系泊缆绳往往无法承受巨大拉力而发生破断,导致码头系泊系统无法继续有效地限制平台运动.为提高自升式平台在码头系泊期间的安全性,需要对缆绳的破断特点进行研究.研究发现,系泊缆绳的破断呈现一定规律,在风浪流冲击的方向,最短的缆绳最易发生破断,其次是最短缆绳附近的缆绳发生后续破断,后续破断的缆绳承受的拉力会依次递增.文中的缆绳破断分析方法可以为海洋平台、船舶系泊系统可靠性校核提供参考.     

深水半潜式钻井平台码头抗台风系泊计算分析

深水半潜式钻井平台在码头舾装的周期较长,为确保安全,需对其码头系泊系统进行计算,以得到合理的系泊布置方式。以某深水半潜式钻井平台的码头系泊系统为例,进行风、流载荷共同作用下的抗台风系泊计算分析,建立了多浮体混合带缆系泊系统。     

系泊索属性对开敞式码头船舶系泊安全的影响分析

结合某工程实例,运用OPTIMOOR系泊分析软件,研究系泊索属性对开敞式码头船舶系泊安全的影响。以减少环境荷载作用下船舶运动量、均衡缆绳张力和减少断缆危险为目标,通过调节缆绳材质、直径,考虑导缆孔到绞盘的距离,增加预张力及缆尾索等方法,以期达到提高开敞式码头船舶系泊安全性的效果,此成果可为码头设计及港口管理人员提供参考。     

开敞式码头系泊缆绳的优化研究

运用OPTIMOOR系泊软件,以减小环境荷载作用下船舶运动量及均衡缆绳张力分布为优化目标,结合江苏某港10万吨级石化码头,通过对比不同的缆绳材质、调整缆绳长度、调节缆绳预张力来优化开敞式码头系泊缆绳的布置。计算结果表明:增加缆绳长度可降低缆绳张力,设置尾缆能显著降低系泊钢缆的动力负荷,减少船舶的运动量;施加合理大小的预张力能有效降低船舶的位移量,均衡缆绳张力;建议大船主缆选用钢缆。     

大型舰船系泊防台风方法探讨

分析码头常规缆绳系泊、链索系泊、水鼓系泊方式的工作原理和应用特点,其中,码头链索防台系泊是一种新的系泊方式,还有待进一步研究,认为大型舰舶应根据自身的条件和系泊环境条件,选择恰当的系泊方式,以保证舰船系泊安全。     

半潜平台码头临时系泊方案设计

考虑半潜平台码头临时系泊需求,利用码头现有系缆柱及设备机具设计不同风速环境作用下码头系泊方案,保持各个方案之间具有连续性,数值模拟中通过输入环境载荷、简化隔离驳护舷建立系泊系统模型,分析常规海况与极限海况下系泊系统受力及运动,评估安全性,并针对极限海况下船体可能产生的触底风险提出调整方案。     

深水系泊缆绳动力特性研究

考虑波浪、海流、顶部浮体运动与海底接触效应的影响,依据集中质量法建立系泊缆绳柔性力学模型,以一座深水半潜式平台的系泊系统为例,对比研究了各种因素对于缆绳动态张力与水中构型的影响程度,最后采用模型试验方法对数值计算结果进行验证。研究表明：缆绳的动态系泊张力主要由浮体运动所引起,可达总张力的20%左右,海流流速可使得缆绳形态出现大变形,导致缆绳卧底长度发生明显改变,危及平台作业安全,波浪与海底摩擦对于缆绳响应的直接作用较小,设计阶段基本可以忽略不计。     

长周期波浪影响下连片式码头系泊布置优化

为改善长周期波浪影响下连片式码头的泊稳条件,结合工程实例,利用数值分析软件分析长周期波浪作用下连片式码头系泊船舶的缆绳张力、船舶运动量特点,提出改善长周期波浪影响下泊位系泊稳定性的关键因素。结果表明,随着波周期的增大,系泊船舶的缆绳张力、船舶运动量均会显著增大;系泊优化的关键在于增加系泊体系的弹性以便吸收船舶的动能量。系泊优化措施包括增加缆绳长度、采用非刚性缆绳系泊或增加缆绳的尼龙尾缆长度。采取系泊优化措施后,可大幅降低长周期波浪作用下缆绳张力,达到系泊布置优化目的。     

大缆材料对旁靠外输系统的动力响应影响分析(英文)

In order to provide a theoretical guide for choosing the material for the hawsers for the FPSO side-by-side offloading system, which is moored by the yoke system, the 3D potential flow theory and full coupled time-domain analysis are presented to study the dynamic response of the offloading system. The Ming Zhu FPSO offloading system in the field BZ25-1 is simulated here; and four different characteristic fiber ropes are used as the material for the hawsers. To acquire an accurate hawser line tension, the polynomial fitting method is used to calculate the nonlinear stiffness of the hawsers. By comparing the hawser lines' tension and the relative motion between the FPSO and the shuttle tanker, a suitable material for the hawser lines is chosen and discussed in this paper. The results indicate that the nonlinear stiffness characteristic of the fiber rope has a small effect on the relative motion of the vessels, but the hawser lines' tension is greatly influenced by the different characteristics of the fiber ropes. The hawser lines' tension with nonlinear stiffness is in accordance with the one with the upper and lower bound linear stiffness, which proves this method of fitting the fiber ropes' nonlinear stiffness is reasonable and reliable.     

船闸输水过程闸室船舶系缆力数值模拟

文章基于“船舶—水流”耦合动力响应,建立了船闸闸室船舶纵向和横向受力方程及其运动控制方程。利用 FLUENT 软件,采用 RNG k-ε三维紊流模型,运用 VOF 法捕捉自由液面,阀门的开启过程及船舶运动利用动网格技术,船舶的运动控制及系缆力的并行计算程序采用用户自定义函数（UDF）进行编写。针对带格栅消能室的船闸集中输水系统,进行了灌水过程的闸室船舶系缆力数值模拟研究,通过与模型试验系缆力过程线的比较,证明了数值方法的正确性和有效性。数值研究了消能室内有无设置辅助消能工情形下的闸室船舶系缆力,并分析了辅助消能工的功能和效果。     

Extreme hawser tension assessment for FPSO vessel during offloading operation in Bohai bay

The Floating Production Storage and Offloading Unit (FPSO) is an offshore vessel that produces and stores crude oil prior to tanker transport.Robust prediction of extreme hawser tensions during Floating Production Storage and Offloading (FPSO) operation is an important safety concern. Excessive hawser tension may occur during offloading operations, posing an operational risk. In this paper, AQWA has been used to analyze vessel response due to hydrodynamic wave loads, acting on a specific FPSO vessel under actual sea conditions. Experimental validation of numerical results has been discussed as well.This paper advocates methodology for estimating extreme response statistics, based on simulations (or measurements). The modified ACER (averaged conditional exceedance rate) method is presented in brief detail. Proposed methodology provides an accurate extreme value prediction, utilizing all available data efficiently. In this study the estimated return level values, obtained by ACER method, are compared to the corresponding return level values obtained by Gumbel method. Based on the overall performance of the proposed method, it is concluded that the improved ACER method can provide more robust and accurate prediction of the extreme hawser tension.Data declustering issue has been addressed. Paper highlights ability of ACER method to account for a set of varying sea state probabilities, as required in engineering long term statistical analysis.Described approach may be well used at the vessel design stage, while defining optimal vessel parameters that would minimize potential FPSO hawser tension.     

大尺度水下综合试验模型拖曳运动特性研究

大尺度水下综合试验模型采用拖缆实现加、减速过程,为了保证其运行稳定性和安全性,基于简化的刚体-弹性体振动模型,分析水下拖曳航行体系统的特性,给出合适的拖缆预紧力;并分析试验模型运动特性,给出保证试验过程中的运动稳定性和安全性的操舵限制条件。     

大型无动力船舶防台系泊系统系缆技术*

防台单点系泊系统是解决大、中型无动力船舶防台锚泊问题的有效途径,而实现防台系泊系统的关键之一是设计简易、实用、可靠的系缆技术.通过对系缆介质、系船环和系缆工艺等方面的综合论述,介绍一套适用于防台系泊系统的系缆技术.     

A stability analysis of tandem offloading systems at sea

In this article, we analyze the linear stability of tandem offloading systems in wind, current, and waves. The wind and current forces are evaluated with the help of published experimental data, while the hydrodynamic coefficients and wave drift forces are rigorously estimated by using a three-dimensional singularity distribution method based on potential theory. The bow hawser and mooring lines are described quasistatically by elastic catenary equations. In order to examine the linear static and dynamic stability of the system, the equations for surge, sway, and yaw are linearized. The effect of design parameters such as turret position, mooring stiffness, and hawser length and stiffness on stability is investigated based on linearized model. The stability analysis clarifies the mechanism of the limit cycle for tandem offloading systems, which is known as fishtailing motion. The theoretical results of the shape and amplitude of the limit cycle are found to be in good agreement with those of simulations and experiments.     

斜面升船机原体水力学试验研究

在小型纵向斜面升船机中,坝顶用链条传动机构转移船厢的布置是可行的,试验中观测了牵引力、系缆力和水体波动,给出了计算这些数值的公式。     

绞缆机滚筒的有限元分析

为了简化计算及节约计算资源,考虑将绞缆机滚筒组件在三维CAD软件SolidWorks中转换为单一零件来达到模拟实际绞缆机滚筒组件的装配关系,通过MSC.Nastran平台,对绞缆机滚筒进行线性静力分析,并在此基础上对滚筒的强度进行校核,从而为绞缆机滚筒进一步合理改进提供参考。     

集中输水系统船闸阀门缓变速开启方式的研究

集中输水系统船闸阀门缓变速开启方式可以有效利用阀门廊道断面尺寸进行输水,从而缩短闸室输水时间。文中结合工程试验研究,介绍了其设计原则及初步研究成果。试验表明,20级变速开启的充水时间可较匀速开启缩短15%左右,而闸室船舶的系缆力仍可满足规范要求。     

Material Selection for Hawsers for a Side-by-side Offloading System

In order to provide a theoretical guide for choosing the material for the hawsers for the FPSO side-by-side offloading system, which is moored by the yoke system, the 3D potential flow theory and full coupled time-domain analysis are presented to study the dynamic response of the offloading system. The MingZhu FPSO offloading system in the field BZ25-1 is simulated here; and four different characteristic fiber ropes are used as the material for the hawsers. To acquire an accurate hawser line tension, the polynomial fitting method is used to calculate the nonlinear stiffness of the hawsers. By comparing the hawser lines＇ tension and the relative motion between the FPSO and the shuttle tanker, a suitable material for the hawser lines is chosen and discussed in this paper. The results indicate that the nonlinear stiffness characteristic of the fiber rope has a small effect on the relative motion of the vessels, but the hawser lines＇ tension is greatly influenced by the different characteristics of the fiber ropes. The hawser lines＇ tension with nonlinear stiffness is in accordance with the one with the upper and lower bound linear stiffness, which proves this method of fitting the fiber ropes＇ nonlinear stiffness is reasonable and reliable.