Dynamic Coupling Analysis of Semisubmersible Platform Float-over Method for Docking Case

In this paper,the multi-body coupled dynamic characteristics of a semisubmersible platform and an HYSY 229 barge were investigated.First,coupled hydrodynamic analysis of the HYSY 229 barge and the semisubmersible platform was performed.Relevant hydrodynamic parameters were obtained using the retardation function method of three-dimensional frequency-domain potential flow theory.The results of the hydrodynamic analysis were highly consistent with the test findings,verifying the accuracy of the multifloating hydrodynamic coupling analysis,and key hydrodynamic parameters were solved for different water depths and the coupling effect.According to the obtained results,the hydrodynamic influence was the largest in shallow waters when the coupling effect was considered.Furthermore,the coupled motion equation combined with viscous damping,fender system,and mooring system was established,and the hydrodynamics,floating body motion,and dynamic response of the fender system were analyzed.Motion analysis revealed good agreement among the surge,sway,and yaw motions of the two floating bodies.However,when the wave period reached 10 s,the motion of the two floating bodies showed severe shock,and a relative motion was also observed.Therefore,excessive constraints should be added between the two floating bodies during construction to ensure construction safety.The numerical analysis and model test results of the semisubmersible platform and HYSY 229 barge at a water depth of 42 m and sea conditions of 0°,45°,and 90° were in good agreement,and the error was less than 5%.The maximum movement of the HYSY 229 barge reached 2.61 m in the sway direction,whereas that of the semisubmersible platform was 2.11 m.During construction,excessive constraints should be added between the two floating bodies to limit their relative movement and ensure construction safety.

风浪联合作用下分布式调谐质量阻尼器对海上半潜漂浮式风机的减振控制

海上半潜漂浮式风机在复杂深海环境下产生有害振动会威胁风机的安全性和耐久性,针对该问题并结合美国NREL的5 MW样机的漂浮平台几何结构构造,提出利用分布式调谐质量阻尼器(Tuned Mass Dampers,TMDs),即分别在漂浮平台的3根浮筒中布置TMD,形成等边三角形布置,对随机风浪联合作用下海上半潜漂浮式风机的平台纵摇振动进行控制。为了更好地描述分布式TMDs对海上半潜漂浮式风机的减振效果,基于拉格朗日方程和模态叠加法,对海上半潜漂浮式风机-TMDs耦合系统提出并建立了9自由度多体动力学模型。基于H_(∞)算法,即以平台纵摇频响函数的峰值为优化目标,对分布式TMDs的参数进行优化设计,优化设计中考虑了3个TMDs之间的耦合关系。对风机-TMDs耦合系统开展了风浪联合作用下的数值模拟,分析了分布式TMDs对平台纵摇响应的减振效果。结果表明:最优设计下的分布式TMDs对海上半潜漂浮式风机平台纵摇振动具有良好的减振性能;在三种不同工况的随机风浪荷载作用下,分布式TMDs对平台纵摇固有频率附近的功率谱密度曲线峰值减振率和标准差减振率能分别达到39%和52%以上。

10 MW级海上风电新型浮式基础结构强度分析

针对应用于50 m水深海域的10 MW海上风力机,设计由三浮筒及三立柱组成的新型浮式基础,建立带有骨材结构的有限元分析模型。对于有关此新型浮式基础的设计波参数,一般选用随机性设计波的方法来确定,对波浪载荷工况下的整体结构。重点研究浮筒的骨材尺寸以及骨材间距对新型浮式基础强度的影响规律,并得到纵横骨材尺寸组合对新型浮式基础整体强度的影响规律。研究表明,新型浮式基础结构高应力区域位于3个浮筒连接处,浮筒板单元应力水平受骨材尺寸和骨材间距的共同影响,采用合适的尺寸间距组合可在应力水平相当的情况下显著降低用钢量。

半潜式起重铺管船SSCV的发展现状及应用

本文从半潜式起重铺管船的发展历史及所具备的作业性能,阐述了半潜式起重铺管船在超大型结构物安装、深水J-Lay海管铺设、深水水下油气设施安装等方面的技术特点及功能,并从专业角度对半潜式起重铺管船与常规起重铺管船的各项特性进行了深入分析对比。

Dynamic Analysis of a 10 MW Floating Offshore Wind Turbine Considering the Tower and Platform Flexibility

Recently,semisubmersible floating offshore wind turbine technologies have received considerable attention.For the coupled simulation of semisubmersible floating offshore wind energy,the platform is usually considered a rigid model,which could affect the calculation accuracy of the dynamic responses.The dynamic responses of a TripleSpar floating offshore wind turbine equipped with a 10 MW offshore wind turbine are discussed herein.The simulation of a floating offshore wind turbine under regular waves,white noise waves,and combined wind-wave conditions is conducted.The effects of the tower and platform flexibility on the motion and force responses of the TripleSpar semisubmersible floating offshore wind turbine are investigated.The results show that the flexibility of the tower and platform can influence the dynamic responses of a TripleSpar semisubmersible floating offshore wind turbine.Considering the flexibility of the tower and platform,the tower and platform pitch motions markedly increased compared with the fully rigid model.Moreover,the force responses,particularly for tower base loads,are considerably influenced by the flexibility of the tower and platform.Thus,the flexibility of the tower and platform for the coupled simulation of floating offshore wind turbines must be appropriately examined.

基于运动响应短期预报的半潜船货物系固分析

提出一种基于波浪运动响应短期预报的货物系固方案评估方法。依据中国船级社《半潜船载运手册编制指南》,针对某半潜船单航次载运重大件货物的特定航线,确定设计波高、风速、谱峰周期范围等参数,使用短期预报方法计算得到运动响应最大可能极限值,根据预报极值直接计算货物惯性载荷,分析系固方案抗滑移、抗翻转能力。

Motion and Dynamic Responses of A Semisubmersible in Freak Waves

The present research aims at clarifying the effects of freak wave on the motion and dynamic responses of a semisubmersible. To reveal the effects of mooring stiffness, two mooring systems were employed in the model tests and time-domain simulations. The 6-DOF motion responses and mooring tensions have been measured and the 3- DOF motions of fairleads were calculated as well. From the time series, trajectories and statistics information, the interactions between the freak wave and the semisubmersible have been demonstrated and the effects of mooring stiffness have been identified. The shortage of numerical simulations based on 3D potential flow theory is presented. Results show that the freak wave is likely to cause large horizontal motions for soft mooring system and to result in extremely large mooring tensions for tight mooring system. Therefore, the freak wave is a real threat for the marine structure, which needs to be carefully considered at design stage.

Multi-Objective Optimization of A Semisubmersible for Ultra-Deep Water

Semisubmersible will work well when oil exploitation goes to ultra-deep water because of its variable load capacities, and good motion performance in extreme waves. It is considered to be a main type of platform while the water depth is more than 3000 meters. This paper establishes a multi-objective optimization model of semisubmersible for ultra-deep water, and it is solved by a multi-objective genetic algorithm--NSGA-Ⅱ. The model is applied to a practical design, and Pareto results are obtained. The effectiveness of the method is verified by hydrodynamic analysis.

6-DOF Motion Assessment of A Hydrodynamic Numerical Simulation of A Semisubmersible Platform Using Prototype Monitoring Data

Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures.In this paper,a hydrodynamic numerical model of“Nanhai Tiaozhan”(NHTZ)FPS platform was established according to its design specifications.The model was assessed with two sets of field monitoring data representing harsh and conventional sea states.The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics,distributions,and spectrum characteristics.The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform.However,the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform.Meanwhile,analysis of the monitoring data revealed that the translational degrees of freedom(DOF)and rotational DOF of the platform were coupled,but these coupled motion states were not apparent in the hydrodynamic simulation.

STUDY OF SEMISUBMERSIBLE ANTI-TYPHOON OFFSHORE PRODUCTION,STORAGE AND MOORING PLATFORM

Most reservoirs explorated offshore China are of medium and small size considered as marginal fields. Economic analysis of fields development shows that the conventional floating production system is still too expensive to be taken for the small sized reservoirs. It is necessary to develop a new concept of early production system. SOECO has developed a new production platform which is called formally Semisubmersible Anti-Typhoon Production Storage and Mooring -- SAPSM. Both the theoretic study and model test have proved that the new platform is a suitable early production system for developing oil reserves offshore China and has the ability to survive in typhoon.

冰载荷下非对称无横撑25000 t SSCV强度评估

为使非对称无横撑的半潜式起重平台具有双吊联合起重25000 t的功能,并满足A0冰级要求,采用设计波法对初始基本设计方案进行总体强度评估;针对冰级A0符号要求,设计处于冰带范围内浮体外壳上的结构尺寸,形成一套完整的结构设计流程,统计钢结构增加量并与初始规范计算对比,结果表明,无横撑结构形式导致甲板盒横舱壁左右舷处、上部连接处应力较高,需进行局部结构分析评估,浮体艏部区域要增加板厚来抵抗冰载荷,冰载荷引起的钢结构增加量所占全船重量比率较小,结构加强后冰带范围附近局部结构强度得到改善,其他部分的总体强度基本不变。

规则波作用下不同构型的近海网箱浸没工况数值研究

The present research work concerns about the hydrodynamic behaviors of the open net offshore fish cages of single,double and 4-cage systems subjected to regular sinusoidal waves.The open net semisubmersible rigid cage is square in shape and analyzed numerically using ANSYS AQWA software.Frequency and time domain analyses are carried out for each case.The hydrodynamic parameters such as added mass,radiation potential damping,motion responses and mooring line tensions are considered as performance indicators to conclude as the best arrangements among three different cages.The single cage and windward side of all cages exhibit identical performance in all hydrodynamic parameters.The leeward side of each cage shows lesser parametric values than the windward side cages.Based on the performance indicators,it is concluded that the grid system containing four cage arrangements provides better performance than three other cage configurations.An experimental model of 1∶75 scale is fabricated and wave flume studies are conducted to validate the present numerical model.The cage is placed at a water depth of 55 cm and subjected to wave heights of 12 cm and 14 cm with wave periods ranging from 0.8 s to 2.2 s with an interval of 0.2 s are considered.The same wave flume boundary conditions are adopted for numerical simulations and results are in good agreement with experimental work results.

半潜式平台纵摇运动高阶谱分析

为了获取半潜式平台纵摇运动特征,系统地开展不同海况条件下的模型试验,并分析海况条件对纵摇运动的影响规律。本文在建立和完善高阶谱分析流程的基础上,通过对波高时历和纵摇时历进行互谱和交叉多谱分析来获得纵摇运动的线性传递函数和二次传递函数。结果表明:线性传递函数与海况关系不大,二次传递函数与海况密切相关;二阶传递函数主要集中于差频为固有频率附近,随着海况的增加,差频为谱峰频率附近的响应也逐渐凸显,据此推测,高海况条件下在波频范围内的纵摇运动具有一定的非线性。

基于锚链可靠性的深水半潜平台设定点追踪控制

装备锚泊辅助动力定位系统的半潜平台运动控制主要目标,是将船舶保持在距离目标位置较小的半径内,同时防止系泊缆发生失效。该文将设定点追踪控制方法应用于配备锚泊辅助动力定位系统的半潜平台,以确保系泊缆的可靠性。根据结构可靠度指数和动态权重系数,建立系泊缆张力的能耗方程,通过求解能耗方程在线计算最优设定点;并基于该方法设计了定位系统控制器,通过时域耦合数值模拟对该方法进行验证与对比。结果表明,在控制参数相同的情况下,文中提出的设定点追踪控制方法可以使系泊缆的可靠度指数保持在相对较高的水平,提高定位精度的同时降低系泊缆张力动态响应幅度。该方法将有助于推动锚泊辅助动力定位系统在半潜平台上的进一步工程应用。

深水半潜式钻井平台DP3动力定位能力分析

以一座深水半潜钻井平台为对象,研究其动力定位系统的定位能力。依据API规范对动力定位能力的分析方法和要求,对半潜平台动力定位系统进行环境载荷的计算与分析,建立了动力定位系统的分析模型,编制了动力定位能力计算程序,针对平台推力系统的完整模式和各种失效模式,计算并绘制了平台在作业工况和待机工况下动力定位能力曲线和静态功率消耗曲线。计算结果表明,该平台的动力定位系统能够满足DP-3级别要求,能保证半潜钻井平台在设计海况下正常作业。

动力定位控位能力分析方法探讨

人类走向深海过程中，动力定位系统将是一个重要的辅助工具。动力定位系统最基本的功能就是通过控制安装的推进器的转速和转向来实现平台的可靠定位。在设计阶段，要通过控位分析来验证所安装的推进器能否完成平台的定位功能；因此，系统的控位能力分析是十分重要的。动力定位系统在定位过程中，推进器发出的推力起到两部分的作用，即：一部分是用来抵抗外界环境力，保持平台不发生漂移（drift-off）；另一部分是用作为控制位置的推力，保持平台不发生过度的位置偏差（drive-off）。对动力定位系统做控位能力分析就是验证：在设计工况下，及现有配备电站容量下，能不能保证平台的定位，平台会不会发生漂移（drift-off）或者过度的位置偏差（drive-off）。另外，它还有着十分重要的经济价值，通过分析，确定安装合适型号的推进器和装置位置，在有限的电站容量下，充分发挥推进器性能。

深水半潜平台框架强度分析研究

随着作业水深和可变载荷的不断增大，深水半潜式平台立柱和浮筒的框架尺寸也在不断加大，进而使得框架强度的重要性日益提高。本文提出一整套详实可行的深水半潜平台框架强度分析方法。该方法分为三个不同的评估阶段和类型：首先，建立平台的整体三维板梁组合模型，对平台框架进行屈服强度及屈曲强度分析；然后，从整体有限元模型中截取局部框架模型，并对模型作进一步的细化处理，分析其在不同舱室压力和静水压力载荷作用下的强度；最后，依据相关船级社的规范对框架的基本尺寸进行校核。本文以某新型深水半潜平台为例，对其立柱框架进行实例计算分析，用以论证本文所提出方法的实用性。通过本文的探讨和分析，为以后类似的工作提供一定的参考依据。

半潜式平台结构整体可靠性分析方法

针对海洋环境中的半潜式平台多方面不确定性,基于半潜式平台结构整体强度分析方法,考虑多种波浪荷载作用的结构响应,采用非线性逐步垮塌分析方法,研究平台在不同控制工况下的极限承载力模型,建立相应的功能函数。根据结构体系可靠度理论和失效模式之间的关系,采用串联体系的可靠度计算方法。最后,对一座具体半潜式平台在100年重现期波浪荷载作用下进行了体系可靠性计算。计算结果表明平台整体可靠度水平由波浪引起的主要结构响应形式决定。通过计算,验证可靠度计算方法具有高效性和可行性,可以为大型深水浮式平台结构的设计、维护和评估提供理论依据。

BINGO9000半潜式钻井平台疲劳强度分析

本文对BINGO9000半潜式钻井平台进行了疲劳强度分析。首先 ,建立了该平台整体三维有限元模型 ,结合北海波浪长期分布资料 ,计算了72种波浪载荷工况下的整体结构应力 ,为管节点结构局部应力分析提供边界条件。其次 ,建立了管节点结构局部有限元模型进行疲劳强度分析。在计算管节点结构应力范围时 ,本文应用热点应力法 ,并根据DNV规范提供的S -N曲线 ,以及Miner线性疲劳累积损伤准则计算出管节点结构的疲劳寿命。本文最后给出了一些有意义的结论 。

深水半潜式钻井平台动力定位系统时域仿真模拟与模型试验

针对一个动力定位系统定位的深水半潜式钻井平台,建立了动力定位系统数值模拟模型,运用了PID控制理论、低通滤波器以及推进器分配方程对动力定位系统进行了仿真。同时,在哈尔滨工程大学深水水池中对该半潜式钻井平台进行了动力定位能力模型试验,试验采用1:50缩尺比模型,加载了推力器模拟系统,利用自主研发的界面控制程序与瑞典的位移测量系统研究模型在不同情况下的动力定位能力。对数值模拟与模型试验结果进行分析,给出了平台在完整工况与推进器部分失效状况时的运动响应与动力定位能力,环境载荷考虑了静水情况与不同风浪流载荷情况,将数值模拟计算结果与试验结果进行了对比。试验结果与计算结果均表明该平台定位能力满足要求。数值模型与试验模型切实可行,可用于动力定位系统的初步设计与仿真模拟。