DP自升式支腿在海底附近作业时的水动力

IF 1.3 4区 工程技术 Q3 ENGINEERING, CIVIL
Nitin D. Thulkar, S. Yamaguchi
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引用次数: 0

摘要

当自升式平台靠近海上资产作业时,腿的放置和移除是动态定位自升式平台最关键的两种操作模式。任何位置偏差都可能导致资产的碰撞和损坏。该行业在动态定位(DP)系统和千斤顶系统之间存在薄弱环节。目前的DP系统在运行时没有任何传感器来识别柱腿和柱腿上的水动力变化,而不同的柱腿和柱腿设计会产生不同的变化。当铲球靠近海底时,必须报告水动力,以避免由DP系统引起的较大位置偏差。本文提出了一种机制来测量这些力,使用计算流体动力学(CFD)分析来分析自升式钻井平台在靠近海底作业时的行为。自升式平台的动态定位(DP)控制系统至少需要23-30分钟的数学模型来学习船舶的水动力行为和对环境的响应。尽管在不同位置之间移动时,DP自升式钻井船为DP模型提供了学习水动力行为的时间,但保持钻井船位置和航向的管嘴却不允许数学模型学习。剩余的电流保持不变,直到spudcan在海底。因此,DP数学模型的建立过程不能帮助DP系统估计剩余电流形式的附加力。由于船舶推进器的响应需要推力和方位(方向)的快速响应,因此在捕集器脱离海床后不久,船舶就会发生漂移。DP系统制造商目前使用无传感器的方法来计算腿和柱塞上的水动力,从而将一个因素纳入数学模型。自升式DP系统解决了两个同时作用在腿上的力。在空气中的腿受到空气动力的影响,而在水中的腿和柱头受到水动力的影响。目前,DP系统使用阻力系数(Cd)来计算阻力,然而,在整个下降和上升过程中,水动力的变化从未被完全考虑。整个操作过程中的这个薄弱环节会导致定位误差,并且通常不会被船舶操作人员发现。风险由副驾驶和千斤顶船长来处理。DP和顶升同时操作模式(SIMOPS)可能会持续15到90分钟,具体取决于顶升速度、作业水深和现场程序。作业区域靠近资产,这增加了与资产碰撞的风险。大多数关于自升式容器的研究都集中在着陆或穿透时作用在腿上的冲击力上,如Elkadi等人(2014)和Kreuzer等人(2014)。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Hydrodynamic Forces of DP Jack-Up Leg when Operating in Vicinity of Seabed
Leg placement and removal are the two most critical operational modes for dynamically positioned jack-ups when working close to an offshore asset. Any positional deviation may lead to collision and damage to the asset. The industry operates with a weak link between the dynamic positioning (DP) system and the jacking system. Current DP systems operate without any sensors identifying the hydrodynamic force variations on the legs and spudcans, which vary between different leg and spudcan designs. When the spudcan is near to the sea bottom, the hydrodynamic force must be reported to avoid large positional deviations driven by the DP system. This article promotes a mechanism to measure these forces using Computational Fluid Dynamics (CFD) analysis to analyze the jack-up behavior, when the spudcan assembly is operating close to the sea bottom. A jack-up’s dynamic positioning (DP) control system requires minimum 23–30 minutes for the mathematical model to learn the vessel’s hydrodynamic behavior and response to the environment. Although when moving between locations, DP jack-up vessels provide time for the DP model to learn the hydrodynamic behavior, the spudcan that holds the vessel position and headings does not allow the mathematical model to learn. The residual current remains constant until the spudcan is in the seabed. As a result, the DP mathematical model-building process does not help the DP system to estimate the additional forces in the form of residual current. Soon after the spudcan detaches from the seabed, the vessel drift occurs because the vessel thrusters’ response need a rapid response of thrust and azimuth (directions). The DP system manufacturers currently use a sensorless approach to account for the hydrodynamic forces on the legs and spudcans to build a factor into the mathematical model. The jack-up DP system addresses two simultaneous forces on the legs. The leg element in the air is subject to aerodynamic effects and the leg and spudcan elements in the water are subject to hydrodynamic effects. DP systems currently use drag coefficients (Cd) to compute drag forces, however the hydrodynamic force variations during the complete lowering and raising processes are never completely considered. This weak link in the overall operation leads to positional error and is generally unrecognized by the vessel operators. The risk falls to DP officer and the jacking master to handle. The DP and jacking simultaneous operations mode (SIMOPS) may easily last between 15 and 90 minutes, depending on jacking speed, operational water depth, and field procedures, on approach to the asset. The area of operation is close to the asset, which increases the risk of collision with the asset. Most of the studies on jack-up vessels focus on impact force acting on the leg during touchdown or penetrations, such as Elkadi et al. (2014) and Kreuzer et al. (2014).
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来源期刊
Journal of Ship Research
Journal of Ship Research 工程技术-工程:海洋
CiteScore
2.80
自引率
0.00%
发文量
12
审稿时长
6 months
期刊介绍: Original and Timely technical papers addressing problems of shipyard techniques and production of merchant and naval ships appear in this quarterly publication. Since its inception, the Journal of Ship Production and Design (formerly the Journal of Ship Production) has been a forum for peer-reviewed, professionally edited papers from academic and industry sources. As such, it has influenced the worldwide development of ship production engineering as a fully qualified professional discipline. The expanded scope seeks papers in additional areas, specifically ship design, including design for production, plus other marine technology topics, such as ship operations, shipping economic, and safety. Each issue contains a well-rounded selection of technical papers relevant to marine professionals.
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