深海采矿旁靠外输双船耦合动力响应分析

随着人口不断上升,人类对资源的需求与日俱增,对陆地资源的开采已经无法满足人类的需求,人们把目光转向了蕴藏丰富矿产资源、生物资源和能源动力资源的海洋。本文针对水深6 000 m海域矿藏开采,采矿船和运输船旁靠外输矿浆,研究双船系统的耦合动力响应。深海采矿船具有动力定位系统,通过系缆连接运输船实施矿浆外输。本文基于双船连接系缆、护舷及双船间隙设置阻尼盖,建立双船耦合动力学模型。考虑不同浪向对动力定位系统进行参数整定和动力定位系统推力优化,计算双船耦合时域运动响应。结果表明：外输过程双船间隙设置阻尼盖建立双船耦合模型是可行的,深海定位系统的参数整定以位移矢量最小和推力功率最小可以实现推力优化,采矿船动力定位系统可以有效控制双船运动,系缆和护舷强度满足要求。     

深海采矿转场工况平台—水下系统耦合动力响应特性研究

针对水深6.0 km深海采矿装备,研究其转场工况平台—水下系统耦合动力响应特性。建立深海采矿平台—输浆管—中继站一体化耦合动力模型,其中采用有限元方法离散输浆管,采用势流理论计算平台水动力,基于Kalman滤波对动力定位系统进行参数整定,优化动力定位系统推力。考虑动力定位系统,计算水动力和采矿平台—输浆管—中继站的频域响应和平台—水下系统耦合时域运动响应,计算得到了平台时域运动响应、水下系统动力响应及动力定位系统推力响应。结果表明：建立的一体化耦合动力分析模型是可行的,可以有效预报平台及水下系统响应;转场0°浪向动力定位系统可以有效控制平台运动;中继站运动较小,输浆管轴力较大,建议将输浆管的浮力材料移动到流速较小的水下范围,可降低拖曳力,有利于输浆管的强度性能。     

垂荡板对半潜式风机基础拖航过程中水动力性能及运动响应的影响分析

垂荡板对半潜式风机基础水动力性能有极大的影响,从而影响基础拖航安装过程的安全。为了研究垂荡板对半潜式基础拖航过程中运动响应的影响,建立了拖缆—WindFloat浮式风机半潜式基础拖航系统模型。首先,基于三维势流理论,采用AQWA开展了拖航系统的频域水动力分析,分析了垂荡板的尺寸及形状对基础水动力性能的影响规律;进一步采用时域方法对拖航系统的运动响应进行分析,探究了垂荡板的尺寸及形状在不同浪向下对基础运动响应的影响规律。结果表明：垂荡板能有效抑制基础的垂荡RAO,但垂荡板形状对基础的水动力性能无明显影响;具有圆形垂荡板的半潜式基础在拖航过程中的运动性能略优于六边形垂荡板,在原设计基础上继续增大垂荡板尺寸对基础运动响应的抑制效果呈现先增大后减小的趋势,说明半潜式风机基础存在一个最优的垂荡板尺寸。     

单点系泊船形养殖设施的水动力性能研究

中国沿海浮式养殖设施受季风和台风等影响不利于多点固定系泊,采用单点系泊方式有利于在位安全。针对船型养殖设施采用单点系泊系统作为系泊装置,能够很好地适应恶劣环境,本文使用 AQWA （Advanced Quantitative Wave Analysis） 软件进行水动力性能的数值分析,对三角浮框和方形浮框不同入射角度下的幅值响应算子 （Response Amplitude Operator,RAOs）、辐射阻尼和一阶波浪力进行频域计算,以及进行水动力时域计算。分析不同工况组合条件下养殖设施的运动响应及系泊力响应,评估在作业海域设施的在位安全性。     

半潜式平台运动及系泊系统特性研究

针对深海半潜式平台及其系泊系统的水动力特性,运用时域耦合的分析方法,对一座水深为1 000 m的半潜式平台,及其悬链线式系泊系统的水动力性能进行探索,获得频域和时域响应结果。同时阐述了平台系泊系统的设计流程,并通过系泊系统参数的变化,研究其特性寻找影响系泊系统作用的一般规律,为平台及其系泊系统设计提供参考。     

不同浪向下大型回转式起重船回转起吊作业过程的动力学分析

随着海洋开发从浅水走向深水,各种特种船舶在海洋工程建设中发挥的作用日益重要。起重船是海洋工程建设的重要工程船舶,是海洋开发的必备工具。为了更好的开发利用海洋资源,有必要进行相关设备的研究。参考某回转式起重船的具体参数,结合该船工作时的具体过程,利用大型水动力分析软件OrcaFlex建立了该起重船回转起吊作业状态下的动力学分析简化模型。通过调节不同海况下的浪向,实现了对大型回转式起重船回转起吊作业过程的的动力学分析,得到了吊物就位时不同浪向下的与接收船甲板的碰撞力、吊缆张力等,对比并分析了不同浪向时吊缆的张力变化,确定了吊物的最小碰撞力和吊缆的张力大小及波浪方向,结合计算结果,给出了大型回转式起重船回转起吊作业的优化设计方案。     

基于全耦合模型的海上吊装作业动力响应特征研究

针对现有海上吊装模拟方法不能有效考虑浮吊船舶—系泊系统—吊物系统之间的动态耦合,难以实现基座回转、吊臂变幅连续模拟问题,基于Matlab/Simulink、ADAMS联合仿真平台建立了海上吊装作业全耦合动力分析模型,探究了中长周期波作用下波浪周期、吊缆收放、基座回转、吊臂变幅等参数变化对吊装作业系统动力响应的影响规律。结果表明,波浪周期接近吊物系统固有周期时会引发共振,导致吊物摇摆幅值显著增加。基座回转、吊臂变幅等因改变了吊物的空间位置从而引发了浮吊船舶倾覆力矩的变化,进而对浮吊船舶运动响应产生显著影响。当基座回转90°后,浮吊船舶的横倾角增加约2.74°。     

转塔位置对FPSO水动力性能的影响

转塔位置是内转塔式FPSO设计中的重要参数,对风标效应以及运动和系泊力等有重要影响.采用时域分析方法分别计算了10万吨级FPSO在不同转塔位置时百年一遇风、浪、流海洋环境条件作用下的运动响应和系泊力,分析了不同转塔位置对FPSO水动力性能的影响.计算结果与模型实验进行了比较,结果表明,转塔位置的变化对FPSO风标效应、转塔系泊力等影响显著.分析结果对于选择理想的转塔位置具有一定的实际意义.     

用于拆平台的双船协同动力定位试验研究

大型海洋结构物的退役和拆除是油气行业面临的一个巨大挑战。双船起重拆除法提供了一种低成本、高效、灵活的解决方案,该方案采用两艘具有动力定位功能的半潜运输船从平台两侧将平台上层组块托起,随后协同托举运输至第三艘半潜运输船上后转运送至陆地。在这个过程中涉及到两艘及三艘船的协同动力定位作业,这对动力定位系统的同步性具有很高要求。多船近距离协同动力定位会受到螺旋桨与螺旋桨、船体与船体及螺旋桨与船体之间的干扰,动力定位的性能会受到影响。为此开展了相应的水池模型试验研究,对复杂环境下多船协同动力定位性能进行了分析,包括定位精度、功率消耗等,并对动力定位风险点进行了深入研究,验证了双船起重拆除法的可行性,并对实际工程的施工提供一定指导意见。     

半潜式平台完全时域耦合运动分析

采用三维频域GREEN函数法计算浮体的水动力特性,并运用非线性有限元法对系泊缆索进行模拟,通过完全时域耦合方法求解整个系泊系统的时域控制方程,得到半潜式平台系统的运动响应和系泊缆索的张力变化情况,并对这些响应结果的波频和低频成分进行了分离,讨论了各频率响应成分对平台系统运动的贡献。     

Dynamic factor analysis considering elastic boom effects in heavy lifting operations

The dynamic factor is the ratio of the maximum dynamic load to the static load acting on the wire ropes between the boom of a floating crane and a cargo. In this paper, the dynamic factor is analyzed based on dynamic simulations of a floating crane and a cargo, considering an elastic boom. For the simulation, we designed a multibody system that consists of a floating crane barge, an elastic boom, and a cargo connected to the boom through wire ropes. The dynamic equations of motion of the system are based on flexible multibody system dynamics. Six-degree-of-freedom motions are considered for the floating crane and for the cargo, and three-dimensional deformations for the elastic boom. The hydrostatic force, the hydrodynamic force, the gravitational force, and the wire rope forces are considered as external forces. The dynamic factor is obtained by numerically solving the equation. The effects of the elastic boom on heavy cargo lifting are discussed by comparing the simulation results of an elastic boom and a rigid boom.     

MOSES软件在系泊浮体运动计算中的应用研究

采用MOSES软件计算某起重船迎浪下的水动力性能和运动响应,并对该船进行缩尺比为1:50的模型试验。通过软件计算结果和试验结果的对比,分析计算模型的网格划分、二阶波浪力计算方法和粘性阻尼等关键参数的选取对MOSES计算系泊浮体运动的影响,为MOSES软件在系泊下运动计算方面提出建议。     

世越号起吊姿态敏感性分析与方案选择

韩国世越号打捞是世界上首次利用托底钢梁原状态整体起吊难船出水的工程。客滚难船装载的货物容易在沉没后发生移位,上层建筑长时间沉没海底后发生泥沙淤积导致难以准确估计整船的重量重心及浮力浮心的位置。利用水池模型试验和数值计算两种方法分别对大型浮吊船单臂架打捞法和双驳船抬吊打捞法进行了难船姿态受重心位置偏移的敏感性分析。水池模型试验中发现,用大型浮吊船单臂架打捞法,世越号的姿态受其重心位置偏移非常敏感,容易发生侧翻;而用双驳船抬吊打捞法,世越号的姿态受其重心位置的影响非常有限,难船和抬浮驳船都可以保持一个较好的姿态。对比水池模型试验的结果,由于难以计及托底钢梁的翘动和滑动现象,数值计算中得到的难船起吊姿态值偏小。双驳船抬吊打捞法被选为打捞世越号的施工方案,其对难船重心位置偏移不敏感的特性得到了现场实证。这个特点为世越号的成功打捞出水起到了关键作用。     

Hydrodynamic Interactions of Three Barges in Close Proximity in A Floatover Installation

The hydrodynamics of side-by-side barges are much more complex than those of a single barge in waves because of wave shielding, viscous effects and water resonance in the gap. In the present study, hydrodynamic coefficients in the frequency domain were calculated for both the system of multiple bodies and the isolated body using both low-order and higher-order boundary-element methods with different element numbers. In these calculations, the damping-lid method was used to modify the free-surface boundary conditions in the gap and to make the hydrodynamic results more reasonable. Then far-field, mid-field and near-field methods were used to calculate wave-drift forces for both the multi-body system and the isolated body. The results show that the higher-order method has faster convergence speed than the low-order method for the multi-body case. Comparison of different methods of computing drift force showed that mid-field and far-field methods have better convergence than the near-field method. In addition, corresponding model tests were performed in the Deepwater Offshore Basin at Shanghai Jiao Tong University. Comparison between numerical and experimental results showed good agreement.     

Model Tests Research on A Float-Over Barge in Shallow Water Under the Undocking Conditions

In this study, the Jinzhou 9-3 CEPD float-over installation project was investigated. During the undocking condition, the water depth of the motion path of the working barge gradually changed from 10.31 m to 9.41 m. The undocking clearance of the HYSY 228 is smaller than 1 m; therefore, the barge shows highly nonlinear hydrodynamic characteristics, and it is difficult to be accurately simulated by numerical analysis. Thus, it is necessary to obtain the hydrodynamic characteristics and laws of the float-over barge at different water depths by using tank model test, to provide some reference and guidance for float-over operations in shallow water.

     

Numerical and Experimental Investigation of Hydrodynamic Interactions of Two VLFS Modules Deployed in Tandem

This paper numerically and experimentally investigates the hydrodynamic interaction between two semi-submersible type VLFS modules in the frequency domain. Model tests were conducted to investigate the relationship between interactions and wave headings. Numerical studies were performed by solving the radiation-diffraction problem and were validated against the experimental results. Motion Response Amplitude Operators (RAOs) were obtained from numerical and experimental studies. The dependency of the hydrodynamic interaction effect on wave headings is clarified. The influence of different wave periods on the motion responses of two-module VLFS and wave elevations in the gap is studied. The results indicate that the hydrodynamic interactions of the two modules are directly related to the wave headings and the periods of the incident wave. The shielding effect plays an important role in short wave, and the influence decreases with the increase of the incident wavelength. The numerical results based on the diffraction-radiation code can give a relatively good estimation to the responses in short wave while for long wave, it would over-predict the response.     

NNFFC-adaptive output feedback trajectory tracking control for a surface ship at high speed

An adaptive output feedback controller based on neural network feedback-feedforward compensator (NNFFC) which drives a surface ship at high speed to track a desired trajectory is designed. The tracking problem of the surface ship at low speed has been widely investigated. However, the coupling interactions among the forces from each degree of freedom (DOF) have not been considered in general. Furthermore, the influence of the hydrodynamic damping is also simplified into a linear form or neglected. On the contrary, coupling interactions and the nonlinear characteristics of the hydrodynamic damping can never be neglected in high speed maneuvering situation. For these reasons, the influence of the nonlinear hydrodynamic damping on the tracking precision is considered in this paper. Since the hydrodynamic coefficients of the surface ship at high speed are very difficult to be accurately estimated as a prior, it will be compensated by NNFFC as an unknown part of the tracking dynamics system. The stability analysis will be given by the Lyapunov theory. It indicates that the proposed control scheme can guarantee that all the signals in the closed-loop system are uniformly ultimately bounded (UUB), and numerical simulations can illustrate the excellent tracking performance of the surface ship at high speed under the proposed control scheme.     

Effects of side keels on patrol vessel safety in astern waves

Planing hull vessel is well-known to have the problem of low damping and susceptible to large roll angles when encountering beam seas especially when stopped or operated at low speed. One approach to reduce this problem is to incorporate a pair of side keels. The effects of the side keels on both roll damping and resistance of a planing hull patrol vessel were experimentally evaluated by varying length, breadth and the position of the side keels. Tests data of the side keels have been presented on the roll damping coefficients and the resistance forces of the vessel. Next, the roll damping coefficients were utilised in time domain simulation program based on a six-degree-of-freedom mathematical model to predict the roll response and assess the vessel safety in astern waves for the case with and without the side keels. The results from the time domain simulation program have indicated that the effects of a pair of side keels can improve the vessel safety.     

海洋平台浮托安装中横荡护舷限位和缓冲性能分析

浮托安装法,是相对于传统吊装法的一种新型海洋平台安装方法,具有起重能力大、作业周期短、安装费用低、适用范围广、操作安全方便等优点,解决了海上大型平台组块的安装问题。为了研究横荡护舷对浮托安装的影响,首先对海洋平台浮托安装中的护舷装置进行了介绍,然后针对某工程实例应用AQWA软件进行了数值模拟,并进行了模型验证。从时域方面对就位状态下的浮托模型进行了耦合动力分析,研究了横荡护舷参数对驳船运动和撞击力的影响规律。研究表明,横荡护舷可以有效地减小驳船运动和撞击力,其限位和缓冲作用与护舷尺寸及护舷刚度均有关。研究结果可为实际浮托安装工程提供重要的参考。     

圆筒型FPSO优化设计与水动力性能分析

针对圆筒型海上储油装置FPSO垂荡运动性能较差、无法安装干式井口的问题,设计了带延伸筒体与矩形阻尼结构的圆筒型FPSO,根据延伸筒体与矩形阻尼结构是否通海分为两种型式。建立水动力计算模型,比较分析不同延伸筒体和阻尼结构型式对FPSO水动力性能的影响。针对南海作业海域,设计了悬链式系泊系统,基于JONSWAP波浪谱对FPSO的运动进行时域预报,并对系泊系统进行校核。分析结果表明:通海型FPSO垂荡固有周期显著提升,可以错开南海百年一遇谱峰周期,通海型FPSO满足钻井、安装干式井口的运动响应要求,系泊系统系缆张力满足规范要求。