共查询到20条相似文献，搜索用时 641 毫秒
1.
新型深海系泊系统及数值分析技术 总被引：8，自引：1，他引：7
随着海洋油气资源开发逐渐向深海转移,传统的悬链式系泊系统在技术和经济上遇到难以逾越的障碍。作为一种新型的适用于深水和超深水环境的系泊系统,绷紧索系泊系统面临广阔的应用前景。文章对这种新型系泊系统的发展情况进行了介绍,基于有限元数值分析技术,对系泊系统的两个关键特性,即系缆的绷紧-松弛特性以及纤维系缆的动刚度特性进行了分析和处理,通过算例考察了深海平台运动引起的系缆力响应。 相似文献
2.
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
3.
海岸浮式活动码头架设区域的选取是方案设计与研究的重点.文中分析了影响海岸浮式活动码头架设区域选取的主客观因素,建立架设区域多属性决策模型,运用综合赋权的方法对各评价指标赋权,采用综合评分的方法对各备选方案进行评分和排序.实例分析表明,运用多属性决策模型解决海岸浮式活动码头架设区域选取问题是可行的、有效的. 相似文献
4.
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
5.
The shape optimization of the 2-dimensional wing in ground effect (WIG) has been performed by the integration of CFD (computational fluid dynamics) and MOGA (multi-objective genetic algorithm). Because of the trade-off between the aerodynamic forces and the height stability, it is difficult to satisfy the design requirements of efficiency and stability at the same time. In this study, the lift coefficient, the lift-drag ratio and the static height stability are chosen as the objective functions to obtain the optimal wing profiles of a WIG craft. An NACA0015 airfoil is used for the baseline model; the aerodynamic characteristics of the base model are compared with that of the optimal solutions. The profile of the airfoil is constructed by four Bezier curves with fourteen control points resulting in the eighteen coordinates, which are adopted as the design variables. The optimal solutions of the multi-objective optimization are not unique but a set of the non-dominated optima: the Pareto frontiers or a Pareto set. As the results of the multi-objective optimization, the forty Pareto optima, which include high-lift, high-efficiency, and more stable airfoils on the edge of the 3-dimensional objective space, are obtained at thirty evolutions of the generation. 相似文献
6.
水下采油设施下放是海上油气工程开发中的重要环节。经过长期发展,人们已研究出多种下放方法,但如何优选恰当的下放方法是尚待解决的问题。考虑海洋环境中可供数据源的复杂性、不确定性与不完整性,多目标、主客观要素并重是优选方法设计的重要准则。针对水下下放方法优选特点,建立对应评价指标体系。考虑评价指标体系多目标优选决策的特点,提出多目标非均一化灰色关联度模型;为更好地体现主客观要素并重并辩证表达决策者的主客观偏好,在非均一化处理中,运用回归原理与靶向偏差评价思想,提出变系数主客观权值修正模型。最后结合具体案例验证模型的可行性与有效性。结果表明,模型能够满足优选对象要求,对类似多目标主客观评价优选模型的建立具有一定借鉴意义。 相似文献
7.
使用相似原理构建缩尺模型是探究大型结构性能的最基本和最优途径。基于PATRAN软件的PCL语言与ISIGHT软件,提出一种联合静动力学、拓扑优化与多目标优化的集装箱相似畸变模型构建方法。利用拓扑优化的SIMP法(Solid Isotropic Material with Penalization)得到缩尺集装箱墙壁结构的最优材料分布,既保证了结构性能又降低了缩尺模型的重量;基于全局多目标算法建立优化模型,采用有限元方法对集装箱性能进行分析,以结构刚度和一阶模态频率为目标函数进行寻优,得到相似模型的最优设计参数。最终利用有限元分析验证该模型的合理性。结果表明:该方法具有一定的通用性,能为其它类似结构的相似模型构建提供参考。 相似文献
8.
《Marine Policy》2014
A multi-objective programming model has been applied to investigate conflicting goals of the Norwegian cod fisheries. The goals included in this article are economic rent and employment. Fisheries managers are confronted with the problem of how best to allocate the total allowable catch (TAC) of cod among eight vessel groups. Compromise solutions taking into account both objectives by giving them equal weights in the multi-objective programming model are calculated and discussed. This article is an extension of an earlier article in which the trade-off analysis was performed using data only for North Norway and one particular year. The present analysis includes the entire Norwegian cod fisheries and is carried out using time series data for 2003–2007, examining the annual variations of key economic and technological parameters of the cod fisheries. Based on the results from compromise programming, the article discusses management and policy implications of reallocation of the TAC by vessel groups. 相似文献
9.
独立B型LNG液舱内部设置舱壁板材及多种桁材,有效缓解了液舱晃荡效应。针对晃荡载荷下的独立B型LNG液舱结构多目标优化,利用规范中的公式计算晃荡载荷,并引入液舱晃荡系数,以期综合反映液舱内部构件对晃荡特性的影响,在此基础上进一步建立以液舱结构重量和液舱晃荡系数为目标的多目标优化模型,采用多目标遗传算法(NCGA),计算得到改进的独立B型LNG液舱结构设计方案。 相似文献
10.
11.
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
12.
Optimum design and global analysis of flexible jumper for an innovative subsurface production system in ultra-deep water 总被引：3，自引：1，他引：2
The study focuses on the flexible jumper issue of Subsurface Tension Leg Production （STLP） system concept, which is considered as a competing alternative system to support well completion devices and rigid risers in ultra-deep water for offshore petroleum production. The paper presents analytical and numerical approaches for the optimum design and global analysis of the flexible jumper. Criteria using catenary concept are developed to define the critical length for optimum design. Based on the criteria, detailed hydrodynamic analyses including quasi-static analysis, modal analysis, and dynamic analysis are performed. Modal analysis with respect to the quasi-static analysis shows that the existence of resonant modes requires special consideration. The results of dynamic analysis confirm the effectiveness of the de-coupled effect from the jumper on STLP system. The approaches developed in the study also have wide application prospect in reference to the optimum design and analysis of any Hybrid Riser （HR） concept. 相似文献
13.
Jing Chen Yan Lin Jun Zhou Huo Ming Xia Zhang Zhuo Shang Ji 《Ocean Engineering》2010,37(11-12):978-988
Ship’s subdivision arrangement is a multi-objective combinatorial optimization problem with multiple nonlinear constraints. This study focuses on finding a methodology for ship’s subdivision arrangement that can guarantee ship’s offshore sequential ballast water exchanging (SBWE) performances in the preliminary design stage. A mathematical model is built using minimizing trims and hull girder longitudinal bending moments and shearing forces occurred in the SBWE as the objectives, and the multiple safety criteria of the SBWE as the constraints. The longitudinal lengths of the ballast water tanks (BWTs) are taken as design variables that will alter within a reasonable length range. An elitist nondominated sorting genetic algorithm (NSGA-II) is utilized to perform the optimization, in which the nondominated sorting mechanism is employed to handle the multiple objectives, and the constraint-domination principle is utilized to handle the multiple constraints. A special crossover operator called the dispersion apportioned allelic (DAA) crossover is introduced to perform the reproduction of the special problem. A real case study of the subdivision arrangement based on the SBWE of a 50,000DWT double hull product tanker is conducted to demonstrate the feasibility and effectiveness of the proposed approach. 相似文献
14.
The Next Generation Subsea Production System (NextGen SPS) is a new concept for petroleum development in ultra-deep water (UDW) areas. It can improve the structural performance of riser as well as provide several operational benefits to subsurface well completion (SWC) equipment. The design of NextGen SPS’s riser system which includes rigid riser and flexible jumper—like the free standing hybrid riser (FSHR), is a very important issue for the definition of NextGen SPS. This paper details an optimization design on the NextGen SPS’s riser system, with the assistance of the design of experiments (DOE) and surrogate model techniques. The optimization model pertaining to riser system is formulated firstly. The DOE is a statistical technique that guides a sensitive study on the behavior of the riser system before the optimization analysis. Structural responses are obtained by the fully coupled methodology. Through such a preliminary study, the effective contribution of each design variable at the riser performance will be known and some general conclusive remarks will be obtained. Based on the DOE results, design variables are screened to improve the efficiency of optimization process. Particle swarm optimization (PSO) method is employed to conduct the optimization analysis. In this analysis, surrogate models, which are developed by back propagation neural network (BPNN), replace the time consuming dynamic analysis to predict structural responses. Latin hypercube sampling (LHS) method is adopted to generate training sample and testing sample for the BPNN. NextGen SPS that operates at a depth of 3000 m is used as the case for this investigation. The efficiency of optimization design is improved by DOE and surrogate techniques, and a reduction of approximately 46% for the riser system cost is achieved. The obtained conclusions have applicability in reference to the engineering design of FSHR and the study procedure will provide reference for study on other new structure concept. 相似文献
15.
根据浮筒配置方案的设计要求和合理性检验准则,给出了方案的优化模型。针对问题的复杂性,结合约束支配的概念,提出了一种改进的将浮筒纵向位置配置和浮筒充气量综合考虑、一体优化多目标进化算法。通过算例分析可知,将多目标进化算法以及约束支配的概念应用到浮筒配置优化方案是可行的、有效的。 相似文献
16.
Neumann-Michell theory-based multi-objective optimization of hull form for a naval surface combatant
A numerical multi-objective optimization procedure is proposed here to describe the development and application of a practical hydrodynamic optimization tool, OPTShip-SJTU. Three components including hull form modification module, hydrodynamic performance evaluation module and optimization module consist of this tool. The free-form deformation (FFD) method and shifting method are utilized as parametric hull surface modification techniques to generate a series of realistic hull forms subjected to geometric constraints, and the Neumann-Michell (NM) theory is implemented to predict the wave drag. Moreover, NSGA-II, a muti-objective genetic algorithm, is adopted to produce pareto-optimal front, and kriging model is used for predicting the total resistance during the optimization process to reduce the computational cost. Additionally, the analysis of variance (ANOVA) method is introduced to represent the influence of each design variable on the objective functions. In present work, a surface combatant DTMB Model 5415 is used as the initial design, and optimal solutions with obvious drag reductions at specific speeds are obtained. Eventually, three of optimal hulls are analyzed by NM theory and a RANS-based CFD solver naoe-FOAM-SJTU respectively. Numerical results confirm the availability and reliability of this multi-objective optimization tool. 相似文献
17.
18.
缓波型立管由于设计参数较多且优化目标之间相互影响,设计结果具有很大的不确定性。随着代理模型和智能优化算法的发展,针对缓波型立管的优化可以提出更好的解决方案。以提高力学性能和经济效益为优化目标,采用基于Kriging插值模型和NSGA-II算法的多目标优化策略,对考虑顶部浮体影响的深水缓波型立管进行动力响应分析,并开展线型—截面双目标优化集成设计和线型—浮筒三目标优化集成设计。将处于不同几何尺度的设计变量进行集成,旨在各目标存在相互竞争的情况下,与截面、浮筒设计形成有效互动以提高线型设计的总体性能。结果表明,Pareto最优解集可提供多个选择方案,以满足工程实际需要。将所选最优方案与初始设计进行对比,并以疲劳性能和成本估算作为优化的校核指标,取得了理想的优化效果。 相似文献
19.
20.
在海洋浮体平台设计初期,为了快速评估设计方案的结构强度水平,需要研究高效的简化方法。本文基于正交异性板理论,综合了平面应力和横向弯曲两种承载方式,改进了板架结构的正交简化评估方法。改进方法克服了原来只针对单一载荷型式的局限性,可以满足组合载荷状态下板架参数的等效变换。为了验证改进方法的适用性和精度水平,分别采用常规方法和改进方法,针对某案例平台的局部板架结构和整体结构开展了强度评估。评估结果表明,采用改进方法得到的结构区域应力水平误差在15%以内,满足初始阶段总强度评估的精度要求。 相似文献