共查询到20条相似文献，搜索用时 93 毫秒
1.
Deep-sea mining (DSM) is an advanced concept. A simulation method of coupled vessel/riser/body system in DSM combined with dynamic positioning (DP) is proposed. Based on the three-dimensional potential flow theory, lumped mass method, and Morison’s equations the dynamic models of the production support vessel, riser and slurry pump are established. A proportion integration differentiation (PID) controller with a nonlinear observer and a thrust allocation unit are used to simulate the DP system. Coupled time domain simulation is implemented with the vessel operated in two DP modes. Results of the vessel and pump motions, riser tension, and thruster forces are obtained. It shows that the pump will be lifted by the riser when the vessel is chasing the next set point. Riser tension is influenced by the wave frequency motions of the vessel in positioning mode and low-frequency motions in tracking mode. The proposed simulation scheme is practical to study the DSM operation. 相似文献
2.
This paper presents fatigue characteristic analysis of a deepwater steel catenary riser (SCR) under ambient excitations. The SCR involves complex nonlinear dynamic behaviors, especially at the touchdown point (TOP) where the riser first touches the seafloor. Owing to the significant interaction with soil, the touchdown zone is difficult to be modeled. Based on Lumped-Mass method and P-y curve, nonlinear springs are used to simulate the SCR-seabed coupled interaction. In case studies, an SCR's dynamic features have been obtained by transient analysis and the structure fatigue assessment has been carried out by S-N approach. The comparative analysis shows that the TOP is the key location where soil-riser interaction rises steeply and minimum fatigue life occurs. Parameters such as ocean environment loads, vessel motions, riser material and geometric parameters are discussed. The results indicate that the vessel motion is the principal factor for the structure fatigue lite distribution. 相似文献
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4.
This paper develops a nonlinear mathematical model to simulate the dynamic motion behavior of the barge equipped with the portable outboard Dynamic Positioning (DP) system in short-crested waves. The self-tuning Proportional-Derivative (PD) controller based on the neural network algorithm is applied to control the thrusters for optimal adjustment of the barge position in waves. In addition to the wave, the current, the wind and the nonlinear drift force are also considered in the calculations. The time domain simulations for the six-degree-of-freedom motions of the barge with the DP system are solved by the 4th order Runge-Kutta method which can compromise the efficiency and the accuracy of the simulations. The technique of the portable alternative DP system developed here can serve as a practical tool to assist those ships without being equipped with the DP facility while the dynamic positioning missions are needed. 相似文献
5.
Fully coupled global analysis of Floating Production Systems, including the vessel, the mooring system and the riser system is described. Design of the system can be a daunting task, involving more than 1000 load cases for global analysis. The primary driver for the mooring system and for the riser system is motion of the vessel. Vessel motions are driven by environmental forces, but are restrained by forces from the mooring and riser systems. Numerical models and procedures that provide accurate and efficient global modeling of the Floating Production System are presented. Both Time Domain and Frequency Domain procedures are included. The accuracy and efficiency of the procedures are illustrated in an example: a large semi with 16 mooring lines and 20 risers. The procedures provide the accuracy and efficiency for use of fully coupled analysis in design of Floating Production Systems from concept selection to final design, installation and operation. 相似文献
6.
驳船横荡运动下海洋立管的动力响应 总被引：1，自引：0，他引：1
海洋浮式生产系统下立管的受力情况复杂,国内的研究大多集中于两端固支或简支的情况。本文则以水面驳船的横荡运动作为立管上端的动力边界条件,将Matteo Luca Facchinetti的尾流振子模型与考虑外流涡激振动作用下海洋立管运动微分方程相结合,得到管道与流体的耦合振动方程,用Hermit插值函数将方程进行有限元离散,并用Newmark时程分析法及迭代法求解,得到管道各点的位移时程曲线。结果表明:立管的振动频率主要由上端驳船的运动频率所确定,随着驳船运动频率的增加,立管中点的位移幅值先增加后减小;在有动边界存在的条件下,改变外流流速对立管中点的位移幅值影响不大。 相似文献
7.
In consideration of the effect of the internal flowing fluid and the external marine environmental condition on the vortex-induced vibration （VIV） of top tensioned riser （Till）, the differential equation is derived based on work-energy principles and the riser near wake dynamics is modeled by Facchinetti＇ s wake oscillator model. Then Galerkin＇ s finite element approximation is implemented to derive the nonlinear matrix equation of the coupled equations and file corresponding numerical programs are compiled which solve the coupled equations directly in the time domain. The comparison of the predicted results with the recent experimental results and the prediction of SHEAR7 is performed. The results show the validity of the proposed method on the prediction of VIV of deep water risers. The effect of internal flow on the dynamic characteristics and dynmnic response of the riser is analyzed and several valuable conelusions are drawn. 相似文献
8.
In consideration of the effect of the internal flowing fluid and the external marine environmental condition on the vortex-induced vibration (VIV) of top tensioned riser (TTR), the differential equation is derived based on work-energy principles and the riser near wake dynamics is modeled by Facchinetti''s wake oscillator model.Then Galerkin''s finite element approximation is implemented to derive the nonlinear matrix equation of the coupled equations and the corresponding numerical programs are compiled which solve the coupled equations directly in the timedomain. The comparison of the predicted results with the recent experimental results and the prediction of SHEAR7is performed. The results show the validity of the proposed method on the prediction of VIV of deep water risers.The effect of internal flow on the dynamic characteristics and dynamic response of the riser is analyzed and severalvaluable conclusions are drawn. 相似文献
9.
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
10.
The hydrodynamic interaction and mechanical coupling effects of two floating platforms connected by elastic lines are investigated by using a time-domain multi-hull/mooring/riser coupled dynamics analysis program. Particular attention is paid to the contribution of off-diagonal hydrodynamic interaction terms on the relative motions during side-by-side offloading operation. In this regard, the exact method (CMM: combined matrix method) including all the vessel and line dynamics, and the 12×12 hydrodynamic coefficients in a combined matrix is developed. The performance of two typical approximation methods (NHI/No Hydrodynamic Interaction: iteration method between two vessels without considering hydrodynamic interaction effects; SMM/Separated Matrix Method: iteration method between two vessels with partially considering hydrodynamic interaction effects, i.e. ignoring off-diagonal cross-coupling terms in the 12×12 hydrodynamic coefficient matrix) is also tested for the same side-by-side offloading operation in two different environmental conditions. The numerical examples show that there exists significant discrepancy at sway and roll modes between the exact and the approximation methods, which means that the cross-coupling (off-diagonal block) terms of the full hydrodynamic coefficient matrix play an important role in the case of side-by-side offloading operation. Therefore, such approximation methods should be used with care. The fender reaction forces, which exhibit large force with contact but no force without contact, are also numerically modeled in the present time-domain simulation study. 相似文献
11.
Utilization of measurements from on-board monitoring systems of marine vessels is a part of shipbuilding industry’s digitalization phase. The data collected can be used to verify and improve vessel’s power system design. Deployment of data-driven statistical models can enhance the knowledge about the power requirements. In this study, we describe a data-driven statistical model that can be used to study and analyze the power requirement of a vessel, which might help to understand the key factors that influence the power and to quantify their contribution. We propose a powerful tool namely, generalized additive model (GAM), which allows us to model nonlinearities. We build the GAM to see the relationship between power consumed and the key influential factors for a power system based on real data from a platform supply vessel (PSV) in a dynamic positioning (DP) mode with diesel-electric configuration. We also describe the importance of feature extraction based on Hilbert Transform to improve the model. In addition, we fit the linear regression (LR) model as a reference model. In the last phase we verify the results of GAM, LR with simulation model from ShipX to show that the data-driven model is within the boundaries of power requirement from simulations. 相似文献
12.
Nonlinear control of an active heave compensation system 总被引：2，自引：0，他引：2
Heave motion of a vessel or a rig has an adverse impact on the response of a drill-string or a riser. To compensate for heave motion, passive and active devices are usually used. Active heave compensators, in which a control system is an essential part, allow conducting operations under more extreme weather conditions than passive ones. This paper presents a constructive method to design a nonlinear controller for an active heave compensation system using an electro-hydraulic system driven by a double rod actuator. The control system reduces the effect of the heave motion of the vessel on the response of the riser by regulating the distance from the upper end of the riser to the seabed. The control development is based on Lyapunov's direct method and disturbance observers. The paper also includes a method to select the control and disturbance observer gains such that actuator saturations are avoided. Stability of the closed loop system is carefully examined. Simulation results illustrate the effectiveness of the proposed control system. 相似文献
13.
LabVIEW设计中压力传感器的RBF神经网络温度补偿 总被引：5，自引：0，他引：5
在石油平台注水压力监测系统设计中 ,采用LabVIEW虚拟仪器平台 ,嵌入逼近能力强和收敛速度快的RBF神经网络 ,以人工环境实验数据为样本进行训练 ,实现了压力传感器的智能网络温度补偿。结果显示 ,此方法能够在压力、温度变化较大的恶劣环境下 ,获得很高的补偿精度。 相似文献
14.
The dynamic analysis of a deepwater floating structure is complicated by the fact that there can be significant coupling between the dynamics of the floating vessel and the attached risers and mooring lines. Furthermore, there are significant nonlinear effects, such as geometric nonlinearities, drag forces, and second order (slow drift) forces on the vessel, and for this reason the governing equations of motion are normally solved in the time domain. This approach is computationally intensive, and the aim of the present work is to develop and validate a more efficient linearized frequency domain approach. To this end, both time and frequency domain models of a coupled vessel/riser/mooring system are developed, which each incorporate both first and second order motions. It is shown that the frequency domain approach yields very good predictions of the system response when benchmarked against the time domain analysis, and the reasons for this are discussed. It is found that the linearization scheme employed for the drag forces on the risers and mooring lines yields a very good estimate of the resulting contribution to slow drift damping. 相似文献
15.
Hull/mooring/riser coupled dynamic analysis and sensitivity study of a tanker-based FPSO 总被引：2，自引：0，他引：2
A computer program is developed for hull/mooring/riser coupled dynamic analysis of a tanker-based turret-moored FPSO (Floating Production Storage and Offloading) in waves, winds, and currents. In this computer program, the floating body is modeled as a rigid body with six degrees of freedom. The first- and second-order wave forces, added mass, and radiation damping at various yaw angles are calculated from the second-order diffraction/radiation panel program WAMIT. The wind and current forces for various yaw angles of FPSO are modeled following the empirical method suggested by OCIMF (Oil Company International Marine Forum).
The mooring/riser dynamics are modeled using a rod theory and finite element method (FEM), with the governing equations described in a generalized coordinate system. The dynamics of hull, mooring lines, and risers are solved simultaneously at each time step in a combined matrix for the specified connection condition. For illustration, semi-taut chain-steel wire-chain mooring lines and steel catenary risers are employed and their effects on global FPSO hull motions are investigated. To better understand the physics related to the motion characteristics of a turret-moored FPSO, the role of various hydrodynamic contributions is analyzed and assessed including the effects of hull and mooring/riser viscous damping, second-order difference-frequency wave-force quadratic transfer functions, and yaw-angle dependent wave forces and hydrodynamic coefficients. To see the effects of hull and mooring/riser coupling and mooring/riser damping more clearly, the case with no drag forces on those slender members is also investigated. The numerical results are compared with MARIN's wave basin experiments. 相似文献
16.
Xiaohong Chen Yu Ding Jun Zhang Pierre Liagre John Niedzwecki Per Teigen 《Ocean Engineering》2006,33(1):93-117
The dynamically coupled interaction between the hull of a floating platform and its risers and tendons plays an important role in the global motions of the platform and the tension loads in the tendons and risers. This is an especially critical design issue in the frequency ranges outside the wave frequencies of significant energy content. This study examines the importance of this coupled dynamic interaction and the effectiveness of different approaches for their prediction. A numerical code, named COUPLE, has been developed for computing the motions and tensions pertaining to a moored floating structure positioned and restrained by its mooring/tendon and riser systems. In this study the experimentally measured motions of a mini-TLP are compared with those computed using COUPLE and alternative predictions based upon quasi-static analysis. The comparisons confirm that COUPLE is able to predict the dynamic interaction between the hull and its tendon and riser systems while the related quasi-static analysis fails. The comparisons also show that wave loads on the mini-TLP can be accurately predicted using the Morison equation provided that the wavelength of incident waves is much longer than the diameters of the columns and pontoons and that the wave kinematics used are sufficiently accurate. Although these findings are based upon the case of a mini-TLP, they are expected to be relevant to a wide range of floating or compliant deepwater structures. 相似文献
17.
In the present study, the dynamic and fatigue characteristics of two types of stress joints are investigated under ocean environmental condition. Connected with the riser and the platform, stress joint at the vessel hang-off position should be one of the main critical design challenges for a steel catenary riser (SCR) in deepwater. When the riser is under a high pressure and deepwater working condition, the stress state for the joint is more complex, and the fatigue damage is easy to occur at this position. Stress joint discussed in this paper includes two types: Tapered Stress Joint (TSJ) and Sleeved Stress Joint (SSJ), and multiaxial fatigue analysis results are given for comparison. Global dynamic analysis for an SCR is performed first, and then the local boundary conditions obtained from the previous analysis are applied to the stress joint FE model for the later dynamic and multiaxial fatigue analysis. Results indicate that the stress level is far lower than the yield limit of material and the damage induced by fatigue needs more attention. Besides, the damage character of the two types of stress joints differs: for TSJ, the place where the stress joint connects with the riser is easy to occur fatigue damage; for SSJ, the most probable position is at the place where the end of the inner sleeve pipe contacts with the riser body. Compared with SSJ, TSJ shows a higher stress level but better fatigue performance, and it will have a higher material cost. In consideration of various factors, designers should choose the most suitable type and also geometric parameters. 相似文献
18.
为了有效地考虑浮体慢漂运动对钢悬链线立管疲劳损伤的影响,提出了波频和慢漂运动组合作用下钢悬链线立管疲劳损伤简化计算的位置组合叠加法。其核心是:基于浮体慢漂运动概率分布选取若干典型慢漂位置,进行波频运动作用下钢悬链线立管动力响应分析;根据钢悬链线立管运动位置变化特征,截取若干慢漂位置对应的波频应力时程叠加到慢漂应力时程上,得到波频和慢漂运动的组合应力时程;编写基于雨流计数法的MATLAB程序处理立管各节点应力,采用海水环境下Do E.E型S-N曲线和Palmgren-Miner累积损伤准则计算立管各节点疲劳损伤。应用位置组合叠加法对某海域500 m水深的立管进行了疲劳分析,并与全耦合法、权重组合叠加法以及波频和慢漂疲劳损伤简单相加法的结果进行了对比,结果表明该方法具有较高的精度和效率。此外,进行了区域设定系数、波浪高度、波浪周期和土壤表面剪切强度等参数对组合作用下立管疲劳损伤的敏感性分析。 相似文献
19.
A full time-domain analysis program is developed for the coupled dynamic analysis of offshore structures. For the hydrodynamic loads, a time domain second order method is developed. In this approach, Taylor series expansions are applied to the body surface and free-surface boundary conditions, and the Stokes perturbation procedure is then used to establish the corresponding boundary value problems with time-independent boundaries. A higher-order boundary element method (HOBEM) is developed to calculate the velocity potential of the resulting flow field at each time step. The free-surface boundary condition is satisfied to the second order by fourth order Adams–Bashforth–Moultn method. An artificial damping layer is adopted on the free surface to avoid the wave reflection. The mooring-line/tendon/riser dynamics are based on the rod theory and the finite element method (FEM), with the governing equations described in a global coordinate system. In the coupled dynamic analysis, the motion equation for the hull and dynamic equations for mooring-lines/tendons/risers are solved simultaneously using the Newmark method. The coupled analysis program is applied for a truss Spar motion response simulation. Numerical results including motions and tensions at the top of mooring-lines/risers are presented, and some significant conclusions are derived. 相似文献
20.
This paper develops an adaptive fuzzy controller for the dynamic positioning (DP) system of vessels with unknown dynamic model parameters and unknown time-varying environmental disturbances. The controller is designed by combining the adaptive fuzzy system with the vectorial backstepping method. An adaptive fuzzy system is employed to approximate the uncertain term induced by unknown dynamic model parameters and unknown time-varying environmental disturbances. It is theoretically proved that the proposed adaptive fuzzy DP controller can make the vessel be maintained at the desired values of its position and heading with arbitrary accuracy, while guaranteeing the uniform ultimate boundedness of all signals in the closed-loop DP control system of vessels. Simulation studies with comparisons on a supply vessel are carried out, and the results illustrate the effectiveness of the proposed control scheme. 相似文献