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Risk free zone study for cylindrical objects dropped into the water 对落入水中的圆柱形物体进行无风险区域研究
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-12-25 DOI: 10.12989/OSE.2016.6.4.377
Gong Xiang, L. Birk, Linxiong Li, Xiaochuan Yu, Yong Luo
2016) Abstract. Dropped objects are among the top ten causes of fatalities and serious injuries in the oil and gas industry (DORIS, 2016). Objects may accidentally fall down from platforms or vessels during lifting or any other offshore operation. Proper planning of lifting operations requires the knowledge of the risk-free zone on the sea bed to protect underwater structures and equipment. To this end a three-dimensional (3D) theory of dynamic motion of dropped cylindrical object is expanded to also consider ocean currents. The expanded theory is integrated into the authors’ Dropped Objects Simulator (DROBS). DROBS is utilized to simulate the trajectories of dropped cylinders falling through uniform currents originating from different directions (incoming angle at 0 o , 90 o , 180 o , and 270 o ). It is found that trajectories and landing points of dropped cylinders are greatly influenced by the direction of current. The initial conditions after the cylinders have fallen into the water are treated as random variables. It is assumed that the corresponding parameters orientation angle, translational velocity, and rotational velocity follow normal distributions. The paper presents results of DROBS simulations for the case of a dropped cylinder with initial drop angle at 60 o through air-water columns without current. Then the Monte Carlo simulations are used for predicting the landing point distributions of dropped cylinders with varying drop angles under current. The resulting landing point distribution plots may be used to identify risk free zones for offshore lifting
2016)抽象。在石油和天然气行业,掉落的物体是导致死亡和重伤的十大原因之一(DORIS, 2016)。在起重或其他海上作业中,可能会有物体从平台或船舶上意外掉落。正确规划起重作业需要了解海床上的无风险区域,以保护水下结构和设备。为此,扩展了圆柱状物体下落的三维动力学运动理论,同时考虑了洋流。扩展的理论被集成到作者的掉落物体模拟器(DROBS)中。利用DROBS来模拟从不同方向(0度、90度、180度和270度入射角)产生的均匀电流中落下的圆柱体的轨迹。研究发现,电流方向对落缸轨迹和落点有较大影响。将钢瓶落水后的初始条件作为随机变量处理。假设相应的参数取向角、平移速度和旋转速度服从正态分布。本文给出了初始落差为60°的圆柱体通过无电流的气-水柱的DROBS模拟结果。在此基础上,利用蒙特卡罗模拟方法预测了在电流作用下不同落点角度的落点分布。所得的着陆点分布图可用于确定海上起重的无风险区
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引用次数: 18
The effect of small forward speed on prediction of wave loads in restricted water depth 小前进速度对限定水深下波浪荷载预测的影响
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-12-25 DOI: 10.12989/OSE.2016.6.4.305
A. Guha, J. Falzarano
. Wave load prediction at zero forward speed using finite depth Green function is a well-established method regularly used in the offshore and marine industry. The forward speed approximation in deep water condition, although with limitations, is also found to be quite useful for engineering applications. However, analysis of vessels with forward speed in finite water depth still requires efficient computing methods. In this paper, a method for analysis of wave induced forces and corresponding motion on freely floating three-dimensional bodies with low to moderate forward speed is presented. A finite depth Green function is developed and incorporated in a 3D frequency domain potential flow based tool to allow consideration of finite (or shallow) water depth conditions. First order forces and moments and mean second order forces and moments in six degree of freedom are obtained. The effect of hull flare angle in predicting added resistance is incorporated. This implementation provides the unique capability of predicting added resistance in finite water depth with flare angle effect using a Green function approach. The results are validated using a half immersed sphere and S-175 ship. Finally, the effect of finite depth on a tanker with forward speed is presented.
。利用有限深度格林函数预测零前进速度下的波浪载荷是近海和海洋工业中常用的一种行之有效的方法。深水条件下的前向速度近似虽然存在一定的局限性,但在工程应用中也有一定的应用价值。然而,在有限水深条件下的船舶正航速分析仍然需要高效的计算方法。本文提出了一种分析低至中等速度自由漂浮的三维物体的波浪力及其运动的方法。开发了有限深度Green函数,并将其集成到基于三维频域势流的工具中,以考虑有限(或浅)水深条件。得到了六自由度的一阶力和矩以及平均二阶力和矩。考虑了船体耀斑角对附加阻力预测的影响。这种实现提供了独特的能力,可以利用Green函数方法预测有限水深下的附加阻力。用半沉球和S-175舰艇验证了结果。最后,给出了有限深度对油轮前进速度的影响。
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引用次数: 2
CFD prediction of vortex induced vibrations and fatigue assessment for deepwater marine risers 深水隔水管涡激振动CFD预测及疲劳评估
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-12-25 DOI: 10.12989/OSE.2016.6.4.325
Chetna Kamble, Hamn-Ching Chen
. Using 3D computational fluid dynamics techniques in recent years have shed significant light on the Vortex Induced Vibrations (VIV) encountered by deep-water marine risers. The fatigue damage accumulated due to these vibrations has posed a great concern to the offshore industry. This paper aims to present an algorithm to predict the crossflow and inline fatigue damage for very long (L/D > 10 3 ) marine risers using a Finite-Analytical Navier-Stokes (FANS) technique coupled with a tensioned beam motion solver and rainflow counting fatigue module. Large Eddy Simulation (LES) method has been used to simulate the turbulence in the flow. An overset grid system is employed to mesh the riser geometry and the wake field around the riser. Risers from NDP (2003) and Miami (2006) experiments are used for simulation with uniform, linearly sheared and non-uniform (non-linearly sheared) current profiles. The simulation results including inline and crossflow motion, modal decomposition, spectral densities and fatigue damage rate are compared to the experimental data and useful conclusions are drawn.
. 近年来,利用三维计算流体动力学技术对深水隔水管遇到的涡激振动(VIV)有了重要的研究。由于这些振动而累积的疲劳损伤引起了海上工业的极大关注。本文旨在提出一种算法,利用有限解析Navier-Stokes (FANS)技术,结合张拉梁运动求解器和雨流计数疲劳模块,预测超长(L/D bbbb10 3)船用隔水管的横流和管内疲劳损伤。采用大涡模拟(LES)方法对流动中的湍流进行了模拟。采用覆盖网格系统对隔水管的几何形状和隔水管周围的尾流场进行网格化。NDP(2003)和Miami(2006)实验中的立管被用于模拟均匀、线性剪切和非均匀(非线性剪切)电流剖面。将模拟结果与实验数据进行了比较,得到了有用的结论,包括内流和横流运动、模态分解、谱密度和疲劳损伤率。
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引用次数: 11
Numerical simulation of dynamic Interactions of an arctic spar with drifting level ice 北极浮冰与水平浮冰动力相互作用的数值模拟
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-12-25 DOI: 10.12989/OSE.2016.6.4.345
H. Jang, H. Kang, Moo-Hyun Kim
This study aims to develop the numerical method to estimate level ice impact load and investigate the dynamic interaction between an arctic Spar with sloped surface and drifting level ice. When the level ice approaches the downward sloped structure, the interaction can be decomposed into three sequential phases: the breaking phase, when ice contacts the structure and is bent by bending moment; the rotating phase, when the broken ice is submerged and rotated underneath the structure; and the sliding phase, when the submerged broken ice becomes parallel to the sloping surface causing buoyancy-induced fictional forces. In each phase, the analytical formulas are constructed to account for the relevant physics and the results are compared to other existing methods or standards. The time-dependent ice load is coupled with hull-riser-mooring coupled dynamic analysis program. Then, the fully coupled program is applied to a moored arctic Spar with sloped surface with drifting level ice. The occurrence of dynamic resonance between ice load and spar motion causing large mooring tension is demonstrated.
本研究旨在建立估算水平冰冲击载荷的数值方法,并研究具有倾斜表面的北极桅杆与漂流水平冰之间的动力相互作用。当水平冰接近向下倾斜的结构时,相互作用可分解为三个连续阶段:冰接触结构并被弯矩弯曲的破碎阶段;旋转阶段,当碎冰被淹没并在结构下旋转时;而在滑动阶段,水下的碎冰与倾斜的表面平行,产生浮力诱导的虚拟力。在每个阶段,分析公式被构建来解释相关的物理,并将结果与其他现有的方法或标准进行比较。采用船体-隔水管-系泊耦合动力分析程序对随时间变化的冰荷载进行耦合分析。然后,将全耦合程序应用于具有倾斜表面和水平浮冰的系泊北极桅杆。论证了冰荷载与梁运动之间存在动力共振,导致系泊张力较大。
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引用次数: 2
A hybrid method for predicting the dynamic response of free-span submarine pipelines 一种预测海底自由跨管道动力响应的混合方法
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-12-25 DOI: 10.12989/OSE.2016.6.4.363
Tongtong Li, Menglan Duan, W. Liang, C. An
. Large numbers of submarine pipelines are laid as the world now is attaching great importance to offshore oil exploitation. Free spanning of submarine pipelines may be caused by seabed unevenness, change of topology, artificial supports, etc. By combining Iwan’s wake oscillator model with the differential equation which describes the vibration behavior of free-span submarine pipelines, the pipe-fluid coupling equation is developed and solved in order to study the effect of both internal and external fluid on the vibration behavior of free-span submarine pipelines. Through generalized integral transform technique (GITT), the governing equation describing the transverse displacement is transformed into a system of second-order ordinary differential equations (ODEs) in temporal variable, eliminating the spatial variable. The MATHEMATICA built-in function NDSolve is then used to numerically solve the transformed ODE system. The good convergence of the eigenfunction expansions proved that this method is applicable for predicting the dynamic response of free-span pipelines subjected to both internal flow and external current.
。随着世界各国对海洋石油开发的高度重视,大量海底管道的铺设。海底管道的自由跨越可能是由于海底的不均匀度、拓扑结构的改变、人工支撑等原因造成的。将Iwan的尾流振子模型与描述自由跨海底管道振动特性的微分方程相结合,建立并求解了管道-流体耦合方程,研究了内外流体对自由跨海底管道振动特性的影响。通过广义积分变换技术(GITT),将描述横向位移的控制方程转化为含时间变量的二阶常微分方程,消除了空间变量。然后使用MATHEMATICA内置函数NDSolve对转换后的ODE系统进行数值求解。本征函数展开式的良好收敛性证明了该方法可用于预测自由跨管道在内外流作用下的动力响应。
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引用次数: 3
Free surface effects on 2-D airfoils and 3-D wings moving over water 自由表面对二维翼型和三维机翼水上运动的影响
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-09-25 DOI: 10.12989/OSE.2016.6.3.245
S. Bal
The iterative boundary element method (IBEM) developed originally before for cavitating two-dimensional (2-D) and three-dimensional (3-D) hydrofoils moving under free surface is modified and applied to the case of 2-D (two-dimensional) airfoils and 3-D (three-dimensional) wings over water. The calculation of the steady-state flow characteristics of an inviscid, incompressible fluid past 2-D airfoils and 3-D wings above free water surface is of practical importance for air-assisted marine vehicles such as some racing boats including catamarans with hydrofoils and WIG (Wing-In-Ground) effect crafts. In the present paper, the effects of free surface both on 2-D airfoils and 3-D wings moving steadily over free water surface are investigated in detail. The iterative numerical method (IBEM) based on the Green’s theorem allows separating the airfoil or wing problems and the free surface problem. Both the 2-D airfoil surface (or 3-D wing surface) and the free surface are modeled with constant strength dipole and constant strength source panels. While the kinematic boundary condition is applied on the airfoil surface or on the wing surface, the linearized kinematic-dynamic combined condition is applied on the free surface. The source strengths on the free surface are expressed in terms of perturbation potential by applying the linearized free surface conditions. No radiation condition is enforced for downstream boundary in 2-D airfoil and 3-D wing cases and transverse boundaries in only 3-D wing case. The method is first applied to 2-D NACA0004 airfoil with angle of attack of four degrees to validate the method. The effects of height of 2-D airfoil from free surface and Froude number on lift and drag coefficients are investigated. The method is also applied to NACA0015 airfoil for another validation with experiments in case of ground effect. The lift coefficient with different clearance values are compared with those of experiments. The numerical method is then applied to NACA0012 airfoil with the angle of attack of five degrees and the effects of Froude number and clearance on the lift and drag coefficients are discussed. The method is lastly applied to a rectangular 3-D wing and the effects of Froude number on wing performance have been investigated. The numerical results for wing moving under free surface have also been compared with those of the same wing moving above free surface. It has been found that the free surface can affect the wing performance significantly.
将之前开发的用于自由水面下空化二维(2d)和三维(3d)水翼的迭代边界元法(IBEM)进行了改进,并应用于水上的二维(2d)翼型和三维(3d)翼型。计算无粘不可压缩流体在自由水面上通过二维翼型和三维机翼的稳态流动特性,对于一些气助海上交通工具,如一些赛艇,包括双体水翼和地入翼(WIG)效应船,具有重要的实际意义。本文详细研究了自由水面对二维翼型和三维机翼在自由水面上稳定运动的影响。基于格林定理的迭代数值方法(IBEM)可以将翼型或机翼问题与自由曲面问题分离开来。二维翼型表面(或三维机翼表面)和自由表面均采用恒强度偶极子和恒强度源面板进行建模。在翼型表面或机翼表面采用运动学边界条件,而在自由表面采用线性化的运动学-动力学组合条件。利用线性化的自由表面条件,用微扰势表示了自由表面上的源强度。在二维翼型和三维翼型情况下,对下游边界不施加辐射条件,在仅三维翼型情况下,对横向边界不施加辐射条件。首先将该方法应用于四度迎角二维NACA0004翼型,验证了该方法的有效性。研究了二维翼型离自由面高度和弗劳德数对升力和阻力系数的影响。并将该方法应用于NACA0015翼型,对地面效应进行了实验验证。将不同间隙值下的升力系数与实验结果进行了比较。将数值计算方法应用于迎角为5度的NACA0012翼型,讨论了弗劳德数和间隙对升力和阻力系数的影响。最后将该方法应用于一个矩形三维机翼,研究了弗劳德数对机翼性能的影响。对自由表面下运动的机翼与自由表面上运动的相同机翼的数值结果进行了比较。研究发现,自由表面对机翼性能有显著影响。
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引用次数: 5
Frequency domain analysis of Froude-Krylov and diffraction forces on TLP TLP上的Froude-Krylov力和衍射力频域分析
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-09-25 DOI: 10.12989/OSE.2016.6.3.233
Ebrahim Malayjerdi, M. R. Tabeshpour
. Tension Leg Platform (TLP) is a floating structure that consists of four columns with large diameter. The diffraction theory is used to calculate the wave force of floating structures with large dimensions (TLP). In this study, the diffraction and Froude-Krylov wave forces of TLP for surge, sway and heave motions and wave force moment for roll, pitch degrees of freedom in different wave periods and three wave approach angles have been investigated. From the numerical results, it can be concluded that the wave force for different wave approach angle is different. There are some humps and hollows in the curve of wave forces and moment in different wave periods (different wavelengths). When wave incidents with angle 0 degree, the moment of diffraction force for pitch in high wave periods (low frequencies) is dominant. The diffraction force for heave in low wave periods (high wave frequencies) is dominant. The phase difference between Froude-Krylov and diffraction forces is important to obtain total wave force.
. 张力腿平台是一种由四根大直径柱组成的浮动结构。采用衍射理论计算了大尺寸浮体结构的波浪力。在本研究中,研究了不同波浪周期和三种波浪进近角下,张力腿平台在浪涌、摇摆和升沉运动时的衍射波力和弗劳德-克雷洛夫波力以及横摇、俯仰自由度运动时的波力力矩。数值结果表明,不同的波浪进近角对波浪力的影响是不同的。在不同波周期(不同波长)的波浪力和力矩曲线上有一些隆起和凹陷。当波浪以0度角入射时,高波周期(低频)的节距绕射力力矩占主导地位。在低波周期(高波频率)下,波浪的衍射力占主导地位。弗劳德-克雷洛夫力和衍射力之间的相位差对于获得总波浪力很重要。
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引用次数: 7
The technical analysis and study of decommissioning and abandonment of offshore oil field surface facilities and subsea system 海上油田地面设施和海底系统退役与废弃的技术分析与研究
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-09-25 DOI: 10.12989/OSE.2016.6.3.289
Guihua Lu, Hongsheng Li, Jia-ren Xiao, Zhihao Li, Mingfeng Xu
With more than 100 years exploration and development of offshore oil, more and more offshore oil fields will gradually lose the economic profit to operate. In this article, to take the target oil field for example, the procedure of decommissioning for FPSO, TCMS, subsea system and well abandonment have been analyzed. Meanwhile, the environment impact and mitigation measure have been proposed. The successful project experience will provide a guide line for the offshore facilities decommissioning and abandonment.
随着海洋石油勘探开发的一百多年,越来越多的海上油田将逐渐失去经营的经济利润。本文以目标油田为例,分析了FPSO、TCMS、海底系统和弃井的退役流程。同时,提出了环境影响及缓解措施。成功的项目经验将为海上设施的退役和废弃提供指导。
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引用次数: 1
Turret location impact on global performance of a thruster-assisted turret-moored FPSO 转塔位置对推进器辅助转塔系泊FPSO整体性能的影响
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-09-25 DOI: 10.12989/OSE.2016.6.3.265
S. W. Kim, Moo-Hyun Kim, H. Kang
{"title":"Turret location impact on global performance of a thruster-assisted turret-moored FPSO","authors":"S. W. Kim, Moo-Hyun Kim, H. Kang","doi":"10.12989/OSE.2016.6.3.265","DOIUrl":"https://doi.org/10.12989/OSE.2016.6.3.265","url":null,"abstract":"","PeriodicalId":44219,"journal":{"name":"Ocean Systems Engineering-An International Journal","volume":"6 1","pages":"265-287"},"PeriodicalIF":0.9,"publicationDate":"2016-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66502732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
An adaptive method of multi-scale edge detection for underwater image 一种水下图像多尺度自适应边缘检测方法
IF 0.9 Q4 ENGINEERING, OCEAN Pub Date : 2016-09-25 DOI: 10.12989/OSE.2016.6.3.217
Liu Bo
{"title":"An adaptive method of multi-scale edge detection for underwater image","authors":"Liu Bo","doi":"10.12989/OSE.2016.6.3.217","DOIUrl":"https://doi.org/10.12989/OSE.2016.6.3.217","url":null,"abstract":"","PeriodicalId":44219,"journal":{"name":"Ocean Systems Engineering-An International Journal","volume":"6 1","pages":"217-231"},"PeriodicalIF":0.9,"publicationDate":"2016-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66502522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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Ocean Systems Engineering-An International Journal
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