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《船舶与海洋工程学报》2021,(2)
The subsea all-electric Christmas tree(XT) is a key equipment in subsea production systems.Once it fails,the marine environment will be seriously polluted.Therefore,strict reliability analysis and measures to improve reliability must be performed before a subsea all-electric XT is launched;such measures are crucial to subsea safe production.A fault-tolerant control system was developed in this paper to improve the reliability of XT.A dual-factor degradation model for electrical control system components was proposed to improve the evaluation accuracy,and the reliability of the control system was analyzed based on the Markov model.The influences of the common cause failure and the failure rate in key components on the reliability and availability of the control system were studied.The impacts of mean time to repair and incomplete repair strategy on the availability of the control system were also investigated.Research results show the key factors that affect system reliability,and a specific method to improve the reliability and availability of the control system was given.This reliability analysis method for the control system could be applied to general all-electric subsea control systems to guide their safe production. 相似文献
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非粘合挠性管是深水和超深水海洋工程开发的重要水下设备之一。有效地将挠性管安装到深水对于大部分水下设备安装承包商来说是一个重要课题。在最近多个深水安装项目中,发现挠性管安装姿态与安装模拟结果相比未能保持一致。主要的原因是挠性管制造商所提供的挠性管名义弯曲刚度无法准确地定义挠性管在安装过程中的受力特性。制造商所提供的弯曲刚度通常比较小,从而过于保守地描述了弯曲曲率。这对于挠性管的设计是可以接受的,但是过于保守估计的挠性管的弯曲曲率对于其安装模拟并非是合理的。与挠性管安装姿态相关联的参数是最小弯曲半径及安装角度。论文阐述了弯曲特性的定义对挠性管安装模拟准确性的影响。选用滞回曲线及其它弯曲刚度常数来定义挠性管的弯曲属性,并对挠性管安装进行了静态及动态安装模拟。与实测的挠性管安装姿态进行了比对,表明采用滞回曲线能较准确地模拟实际的挠性管安装姿态。因此,采用滞回曲线作为挠性管安装属性进行安装模拟是一种较有效及准确的方法。 相似文献
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《船舶与海洋工程学报》2015,(3)
A subsea flowline jumper(FJ) is a basic connected component for the wet oil tree, subsea pipeline and riser base, and it plays an irreplaceable role in the subsea production system. During the installation of FJ, collisions often happen between FJ and other equipment, which may cause serious damage. Besides, as the operating water depth increases, the demand for the installation equipments, such as the crane and winch, will increase. The research of deepwater FJ installation in China is still in the primary stage, thus an installation method for the deepwater FJ is proposed in this paper. Finite element models of a typical M-shaped FJ installation system are built to simulate the installation procedures. Analysis results show that the installation steps designed are feasible and valid for the deepwater FJ. In order to ensure the safety of the installation process, the collision-sensitive analysis for the FJ is conducted, and results show that it is necessary to set the pick up speed at a proper value, in order to avoid collision in the installation process. Besides, the mechanical characteristics of FJ during the installation are investigated under a range of environmental conditions and it is found that the maximum stress of the FJ always happens at its central position. The basic requirements for the installation equipment are also obtained through the analysis of the main installation steps. 相似文献
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To overcome the current difficulties of high-precision machining and the high manufacturing and maintenance costs of spherical seals for deep-water drilling ball joints, a new spherical seal technique is proposed in this paper. The spherical seal is mainly composed of silicone rubber and polytetrafluoroethylene(PTFE). Rational structural design makes the seal independent from the ball and other components, making it easy to replace if leakage occurs at its surface. PTFE can elastically deform over a certain deformation range, which guarantees that two sealing surfaces fit tightly together. O-Ring and PTFE elasticity makes up for any lack of accuracy during spherical machining and decreases the machining precision requirements for spherical surfaces. Using a finite element technique and nonlinear theory, the performance of the spherical seal under the influence of various factors is determined. The results show that the spherical seal designed in this paper exhibits excellent sealing performance under lowtemperature and high-pressure conditions. The spherical seal, a combination of an O-ring and PTFE, has the advantages of cheap manufacturing and maintenance costs and excellent sealing performance. 相似文献
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脐带缆深水安装的参数影响分析(英文) 总被引:1,自引:0,他引:1
随着水深的增加引起外部压力的增大和脐带缆的重量相应增加,且由于海洋环境载荷和浮体的运动引起复杂的动力特性使得脐带缆的受力复杂,其安全性受到很大的挑战,故深水安装是脐带缆的关键问题之一。文章详细分析了安装过程中不同浮力块的布置方式(不同尺寸,长度和布置位置)和波浪与流的方向对脐带缆的影响。利用悬链线方程构建自由悬挂的脐带缆的模型,然后施加浮力与环境载荷得到动态脐带缆的安装模型。通过对比分析表明,浮力块的布置方案和波浪与流的方向对脐带缆的安装都有很大的影响,上述这些参数在安装中需要给予重视。 相似文献
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Scour depth prediction of offshore pipelines is of great significance to the design and construction of the submarine pipeline projects. In this paper, based on the CFD software package FLUENT and User Defined Function(UDF), an Eulerian two-phase model, which includes an Euler-Euler coupled model for water and sediment phases, and a turbulent model for the fluid phase, is adopted to predict the scour depth around pipelines. The model is verified by observation data obtained from laboratory experiments. On the basis of the simulations, the factors affecting the scour depth, including the effects of incipient velocity, pipe diameter and sediment particle size and so on, were investigated. Meanwhile, according to formulas of incipient velocity of various sediments, approximate calculation on theoretical scour depths is developed for pipelines of seven stations in the South China Sea, where engineering application information is available. 相似文献
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桩基式导管架平台正逐步由浅海向深海发展。深水导管架由于其质量与外形尺寸巨大,对设计、建造、安装提出了更严格的要求。叙述了深水导管架安装分析的一般过程和方法,介绍了MOSES程序在深水导管架安装分析中的使用。 相似文献
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Gunawan Kunihiro Hamada Kakeru Kunihiro Allessandro Setyo Anggito Utomo Michael Ahli Raymond Lesmana Cornelius Yutaka Kobayashi Tadashi Yoshimoto Takanobu Shimizu 《船舶与海洋工程学报》2022,(2):170-178
In the shipbuilding industry, market competition is currently operating in an intense state. To be able to strive in the global market, the shipbuilders must able to produce ships that are more efficient and can be constructed in a relatively short amount of time. The piping layouts in the engine room requires a lot of time for the designer to design the best possible route and in a way are not the most efficient route. This paper presents an automatic piping support system in the ship’s engine ... 相似文献
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《船舶与海洋工程学报》2020,(1)
Modern processing plants use a variety of control loop networks to deliver a finished product to the market. Such control loops,like control valves, are designed to keep process variables such as pressure, temperature, speed, flow, etc. within the appropriate operating range and to ensure a quality product is produced. All control valves have a bypass so that production can proceed if maintenance is needed for the control valve as part of the control loop. The important point is that in both operation and maintenance situations, the bypass valve and the control valve should have approximately the same flow capacity to provide nearly the same amount of pressure. This paper presents a case study in seawater service on the selection of manual bypass valves for a 16″ control valve in class 150 and titanium material. A 16″ butterfly valve of class 150 was chosen for the control valve bypass, which provided a much higher flow capacity than the control valve. In this paper, four solutions are recommended to achieve the same coefficient value(Cv) for the control and bypass valve. Using the reduced size butterfly valve could be the cheapest and best solution. On the other hand, selecting the same control valve for bypass line is the most expensive but maybe the most reliable solution. Using a flow orifice for throttling could be ranked as the second expensive option and the second reliable one. Selection of butterfly valve for throttling is the second cheapest option, but it has the least reliability. Different parameters such as space and weight saving, cost as well as reliability have been considered in evaluation of different solutions. 相似文献
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In this paper, a numerical investigation of a float-over installation for an offshore platform is presented to verify the feasibility of the actual installation. The hydrodynamic performance of a T-barge is investigated in the frequency domain, and the coupled motions are analyzed in the time domain. We then compare with those of the model test and determine that the response amplitude operator and the time series agree quite well. The barge exhibits favorable hydrodynamic behavior in the considered sea state, and the equipment loads are allowable. The mooring system and sway fender forces are within the permissible range. Based on these results,we can verify that the actual installation of the offshore platform is feasible. We accurately simulated many important factors and effectively reduced the risk associated with the offshore installation, which is of great importance. As such, we demonstrate that the numerical simulation of the float-over installation for offshore platforms has practical engineering significance. 相似文献
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《船舶标准化工程师》2015,(1)
结合对海管悬空的研究以及深水项目经验,重点描述了深水段海底管道悬跨段的水泥压块的陆地制作、运输和海上安装的施工过程及检验。以期通过介绍使相关方对深水悬跨段的水泥压块处理方式有所了解,并为今后类似项目提供参考和帮助。 相似文献
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深水导管架滑移下水的安装分析技术和设计方法 总被引:1,自引:0,他引:1
导管架滑移下水是安装重型导管架的一种常见的方式,20世纪70年代初国外已开始在海上实施导管架的滑移下水,80年代初,有关导管架滑移下水的数值模拟分析和安装技术已趋于成熟.随着我国对海上深水油田的进一步开发,吸收国外的先进经验,掌握这方面的分析技术并应用于我国深水开发工程上的需要尤为紧迫.在参阅OTC论文、国外的相关出版物和规范的基础上,对导管架滑移下水过程的分析方法和设计方法进行了论述,并结合一个工程算例加以分析,算例中使用的软件为MOSES. 相似文献
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《船舶与海洋工程学报》2017,(1)
The effect of rigid bed proximity on flow parameters and hydrodynamic loads in offshore pipelines exposed to turbulent flow is investigated numerically. The Galerkin finite volume method is employed to solve the unsteady incompressible 2 D Navier–Stokes equations. The large eddy simulation turbulence model is solved using the artificial compressibility method and dual time-stepping approach. The proposed algorithm is developed for a wide range of turbulent flows with Reynolds numbers of 9500 to 1.5×104. Evaluation of the developed numerical model shows that the proposed technique is capable of properly predicting hydrodynamic forces and simulating the flow pattern. The obtained results show that the lift and drag coefficients are strongly affected by the gap ratio. The mean drag coefficient slightly increases as the gap ratio increases, although the mean lift coefficient rapidly decreases. The vortex shedding suppression happen at the gap ratio of less than 0.2. 相似文献
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《船舶与海洋工程学报》2021,(1)
Subsea pipelines passing through the shallow area are physically protected against the environmental, accidental, and operational loads by trenching and backfilling. Depending on construction methodology, environmental loads, and seabed soil properties, the stiffness of backfilling material may become largely different from the native ground(softer than native ground in most of the cases). The different stiffness between the backfill and native ground affects the soil failure mechanisms and lateral soil resistance against large pipeline displacements that may happen due to ground movement, landslides, ice gouging, and drag embedment anchors. This important aspect is not considered by current design codes. In this paper, the effect of trench-backfill stiffness difference on lateral pipeline-backfill-trench interaction was investigated by performing centrifuge tests. The soil deformations and failure mechanisms were obtained by particle image velocimetry(PIV) analysis. Three experiments were conducted by using three different backfills including loose sand, slurry, and chunky clay that represent the purchased, natural in-fill, and preexcavated materials, respectively. The study shows that the current design codes underestimate the lateral soil resistance for small to moderate pipe displacements inside the trench and overestimate it for large lateral displacement, where the pipeline is penetrating into the trench wall. 相似文献
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《船舶与海洋工程学报》2019,(4)
Nowadays, an increasing number of ships and marine structures are manufactured and inevitably operated in rough sea. As a result, some phenomena related to the violent fluid-elastic structure interactions(e.g., hydrodynamic slamming on marine vessels, tsunami impact on onshore structures, and sloshing in liquid containers) have aroused huge challenges to ocean engineering fields. In this paper, the moving particle semi-implicit(MPS) method and finite element method(FEM) coupled method is proposed for use in numerical investigations of the interaction between a regular wave and a horizontal suspended structure. The fluid domain calculated by the MPS method is dispersed into fluid particles, and the structure domain solved by the FEM method is dispersed into beam elements. The generation of the 2D regular wave is firstly conducted, and convergence verification is performed to determine appropriate particle spacing for the simulation. Next, the regular wave interacting with a rigid structure is initially performed and verified through the comparison with the laboratory experiments. By verification, the MPS-FEM coupled method can be applied to fluid-structure interaction(FSI) problems with waves. On this basis, taking the flexibility of structure into consideration, the elastic dynamic response of the structure subjected to the wave slamming is investigated, including the evolutions of the free surface, the variation of the wave impact pressures, the velocity distribution,and the structural deformation response. By comparison with the rigid case, the effects of the structural flexibility on wave-elastic structure interaction can be obtained. 相似文献
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船舶深水抛锚方法分析 总被引:1,自引:1,他引:0
由于抛锚方案选择不当、抛锚方法应用不当等原因.极易出现抛锚安全问题,深水抛锚时容易出现出链速度太快刹不住而丢失锚链,深水起锚时由于出链太长容易出现锚机力量不够绞不起锚链而丢失锚链等事故.本文针对一起具体的深水抛锚丢锚事故,运用数理分析方法对船舶深水抛锚的动力学原理进行了分析,给出了2个极限水深的计算公式,对船舶深水安全抛锚提供了数理支持. 相似文献