Dynamic Analysis of Turret-Moored FPSO System in Freak Wave

Freak wave is the common wave which has significant wave height and irregular wave shape, and it is easy to damage offshore structure extremely. The FPSOs（Floating Production Storage and Offloading） suffer from the environment loads, including the freak wave. The freak waves were generated based on the improved phase modulation model, and the coupling model of FPSO-SPM（Single Point Mooring） was established by considering internal-turret FPSO and its mooring system. The dynamic response characteristics of both FPSO and SPM affected by the freak wave were analyzed in the time domain. According to the results, the freak waves generated by original phase modulation model mainly affect the 2nd-order wave loads. However, the freak waves which are generated by random frequencies phase modulation model affect both 1st-order and 2nd-order wave loads on FPSO. What is more, compared with the irregular waves, the dynamic responses of mooring system are larger in the freak waves, but its amplitude lags behind the peak of the freak wave.

Investigation of Performance of Turret Assembly in Inboard Turret Mooring System

To fulfil the need of development of offshore oil floating production system, the performance of turret assembly in an inboard turret mooring system has been investigated in the paper. By means of systematic evaluation, the optimal structure of the turret for single-point mooring systems has been determined. Through model tests of a turret mooring system, several groups of data such as forces, moments and displacements under different environmental conditions have been obtained. Stresses and strains of the turret structure have been calculated by means of the finite element method corresponding to the situation in the model experiment. The study shows that the selected turret structure and the designed turret assembly are technically feasible.

Failure Statistics Analysis Based on Bayesian Theory: A Study of FPSO Internal Turret Leakage

The load and corrosion caused by the harsh marine environment lead to the severe degradation of offshore equipment and to their compromised security and reliability. In the quantitative risk analysis, the failure models are difficult to establish through traditional statistical methods. Hence, the calculation of the occurrence probability of small sample events is often met with great uncertainty. In this study, the Bayesian statistical method is implemented to analyze the oil and gas leakages of FPSO internal turret, which is a typical small sample risk but could lead to severe losses.According to the corresponding failure mechanism, two Bayesian statistical models using the Weibull distribution and logarithmic normal distribution as the population distribution are established, and the posterior distribution of the corresponding parameters is calculated. The optimal Bayesian statistical model is determined according to the Bayesian information criterion and Akaike criterion. On the basis of the determined optimal model, the corresponding reliability index is solved to provide basic data for the subsequent risk assessments of FPSO systems.

Design Curves for Mooring Lines of Turret Mooring Systems

This paper presents a series of design curves to aid in the selection of turret mooring systems for tankers based Floating Production Storage and Offloading (FPSO) systems. These curves are appropriate to water depths ranging from 100 m to 600 m. The curves can be used as a preliminary design tool, allowing the designer to quickly evaluate alternative mooring system configurations, including the number of mooring lines, the characteristics of chain and wire rope to be deployed and the. initial tension. With a knowledge of the total environmental force and vessel motion characteristics, the designer can determine the appropriate system for closer evaluation.

Strength Analysis of Turret Mooring Productive/Storage Tanker

The longitudinal strength of turret mooring productive/storage tanker is studied. A numerical example has been implemented according to the method presented in this paper to give practical illustration. From the results of the numerical example, it is concluded that the turret hole located near the forward of the amidships has small effect on the longitudinal strength of the ship hull. As for design extreme value of wave bending moment of storage tanker, statistic method is a more reasonable methodology, especially with the consideration of the servere environmental conditions. The primary estimation of design section modulus of turret storage tanker can be determined by this design bending moment.

Dynamic Analysis of a Turret-Moored Tanker

In this paper, the second-order perturbation method in frequency domain is used to calculate RAO and spectra of motion and mooring line tension of a turret-moored tanker in ballast condition. The calculated results are compared with corresponding experiment results. In the experiment the wave heading is 180 degrees, and the wave spectra is the P-M spectrum and white noise spectrum. In the theoretical calculations, the damping coefficient of slow oscillation of the tanker is determined on the basis of the damping obtained from a test of irregular waves where the mooring system is replaced by a nonlinear spring with nonlinear stiffness similar to that of the mooring system. From the comparison between theoretical calculations and experiment al results, it can be found that the theoretical results obtained by the second-order perturbation method in frequency domain are in good agreement with the experimental results, indicating that the damping coefficient of slow oscillation of the tanker required in frequency domain calculation can be determined by reference to the damping coefficient of the tanker moored by a spring system in irregular waves, and the second-order perturbation method can be used to analyze the dynamic response of a turret-moored tanker.

内转塔式单点系泊系统解脱施工方案研究

南海某油田浮式生产储存卸油船舶(FPSO)为内转塔式单点系泊系统(STP),以该内转塔式单点系泊系统解脱作业为例,开展适用于中国南海海域FPSO解脱施工方案研究,分析解脱施工中关键作业节点的施工方法,为今后南海海域FPSO解脱施工提供参考。

YB518型盒外透明纸包装机折叠转塔离合器调校工装的研制

为解决YB518型盒外透明纸包装机折叠转塔离合器在挤烟时不能及时脱开、安装时扭矩调整困难等问题,研制一种可以实现转塔离合器定量调校的工装。通过使用ANAYS Workbench软件对工装的重要零件压力弹簧进行有限元模拟仿真,确定弹簧材料的选择。利用故障停机率拟合线得出转塔离合器调校时的最佳扭矩值为35N·m。使用该工装对YB518型盒外透明纸包装机折叠转塔离合器进行调校后,转塔离合器脱开率由29.54%提高至94.54%,挤烟平均停机时间缩短了64.71%,降低了设备维修保养时的劳动强度,提高了设备生产效率。此外,通过调节直径,该工装能够适用于多种尺寸型号的转塔离合器,实用性强。

复合磨床砂轮架模态分析与试验研究

基于赫兹接触理论建立了轴承滚动结合部接触模型,采用弹簧阻尼单元代替轴承滚子结合部,在ABAQUS有限元分析软件建立复合磨床砂轮架转塔有限元模型,对转塔结构进行模态分析。利用LMS结构试验系统对转塔结构进行模态测试与分析。试验表明,采用弹簧阻尼单元模拟轴承滚动结合部的有限元模态分析与动态试验结果吻合,验证了该方法的可行性。弹簧阻尼单元替代轴承可以减小建模难度,并为砂轮工作转频和转塔结构优化提供参考依据。

连铸大包回转支承状态劣化的几种数字表征

连铸大包回转支承状态监控目前有传动电机电流监控、润滑油品理化指标检测以及应力波检测等几种有效方法,分别采用这几种方法对回转支承整个劣化过程进行了数据采集和分析,并通过现场解体后的现象和数据对几种方法预判结果进行了验证,可为低速重载类设备状态维护提供参考。

LF精炼炉钢包回转台驱动系统设计与分析

LF炉是整个钢铁精炼工艺过程中最为重要的设备,具有脱硫、脱氧,微调钢水成分的作用,对提高钢水品质具有重要作用;是每个钢企生产优钢特钢的必备设备。现有LF精炼炉主要结构型式分为双车式、回转台式以及电极旋转式。回转台式LF炉其特点是利用回转台的自转将钢水从等待工位转运钢水至冶炼工位进行冶炼;回转台式LF炉具有占地面积小,使用安全可靠,维护保养工作量小,效率高等优势。回转台作为LF精炼炉的重要组成设备,对整个精炼炉安全运行有着重要的作用;而回转台的平稳运行又取决于驱动装置设计的可靠性。针对回转台的驱动装置设计进行分析。通过对回转台驱动系统基础数据的计算、电机和减速机的选型,提出一个安全、可靠的设计方案,以便其他设计者进行参考。

涡流发生器对半球形激光转塔跨声速流场影响数值研究

激光转塔的跨声速绕流场使得机载激光平台面临着严峻的气动光学挑战。为对激光转塔的跨声速流场被动控制提供基本的理论支撑,本文利用了改进亚格子尺度的改进延迟脱体涡模拟(IDDES)方法,针对细长圆柱的针状涡流发生器,对跨声速条件下半球形机载激光转塔的绕流场进行了流动控制数值研究。结果表明,针状涡流发生器引入了明显的二次流特征,削弱了来流能量,导致激光转塔顶部激波强度受到影响,进而影响了激光转塔尾迹区的分离泡尺寸;激光转塔尾迹的横向摆动和纵向波动特征的时空特性并未受到涡流发生器的明显影响,而动态模态分解(DMD)结果指出了当涡流发生器存在时,激光转塔尾迹的纵向波动模态能量具有明显的衰减,合理地对应了尾迹分离泡形态的改变,揭示了本文研究的涡流发生器对激光转塔尾迹分离区的抑制作用,为以被动控制方法来抑制激光转塔气动光学效应提供了依据。

Numerical Investigation on the Hydrodynamic Diference Between Internal and External Turret-Moored FLNG

Motion responses of the floating liquefied natural gas(FLNG)hull and the mooring loads in a 100-year return environmental condition are predicted with the help of the well known coupled dynamic analysis code DeepC.A ship-shaped turret-moored FLNG moored by 4×3 chain-polyester-chain lines in 1.5 km depth of water is studied.Two types of turrets such as internal and external turrets,resulting from diferent locations of the turrets,are adopted respectively in the numerical simulations.Motion responses of the FLNG hull and forces of the mooring lines obtained from the internal turret case and external turret case are compared with each other.Significant diferences are obtained.Statistic analysis is also used to analyze the comparison results,and efects of the turret location on the FLNG hydrodynamic characteristics are summed up.The conclusion regarding the hydrodynamic diferences between internal and external turret-moored FLNG systems would provide help for design of the FLNG system.

某转塔舱运输辅助支撑机构设计与分析

提出了一种用于某偏心转塔舱运输的辅助支撑机构,采用电动缸驱动的连杆机构,并利用连杆的死点位置有效提高了机构的负载能力,实现了机构的小型化及轻量化设计。首先对该转塔舱运输过程中的载荷及连杆机构基本原理进行分析,并根据摩擦因数、导向段弧形导轨长度及连杆自锁角度等参数,对机构进行自锁分析;然后对连杆机构进行结构设计,并根据具体尺寸参数对机构进行运动学及动力学分析;最后进行NX动力学分析、有限元仿真及试验,验证了所提连杆式辅助支撑机构的运动能力及承载能力,证明了该辅助支撑机构设计的可行性与实用性。

运用FANUC信号追踪功能解决电气故障的方法研究

设备电气故障通常为软故障,原因不易发现,日常维修过程中凭借经验判断费时费力、准确度低。当前工业发展迅速,生产节拍要求越来越高,设备出现故障后需要快速精准恢复,给设备维护人员带来挑战。文章以数控车床CK7530F刀塔故障为例,结合刀塔电气控制原理,利用FANUC系统信号追踪功能,总结出一套针对电气故障维修的思路和方法,有利于数控设备维护工作效率的提高。

基于ANSYS的矿用掘进机回转台振动疲劳分析方法

掘进机截割过程易受到强冲击载荷而导致回转台产生振动疲劳现象,对作业的可靠性和稳定性影响较大。经分析掘进机回转台的作业原理,依据Palmgram-Miner疲劳判断法则,利用ANSYS仿真软件对回转台振动疲劳情况进行分析。结果表明:回转台X轴向的振动对回转台疲劳损伤影响较大,通过减振能够较好的提升回转台的整体寿命;回转台与油缸连接的4个销轴位置易产生疲劳损坏现象,最小循环载荷为38965次;仿真结果与现实情况相一致,分析方法具备一定的合理性与可行性,能够作为回转台结构优化和改进的参考依据。

FPSO转塔系泊止链器安装工艺与拖航固定设计

针对我国南海深水浮式生产储卸油装置(FPSO)转塔单点系泊的关键零件止链器,进行安装工艺过程设计模拟和拖航固定设计的有限元分析。结果表明:止链器集成安装的关键点是吊装过程通过姿态调整与锚链盘U型槽配合;满足止链器安装精度的核心是节圆柱与耳轴转动平稳;止链器拖航固定的张紧链是应力薄弱点,在选型设计中应保守考虑使用1根张紧链的工况。实际工程应用验证了止链器安装工艺与拖航固定设计方案满足可靠性要求,为南中国海类似工程提供了直接经验。

T型光电转塔光具座结构研究

T型光电转塔左、右两侧的光具座上分别安装有电视摄像机、红外热像仪和激光测距机等光电传感器,针对某T型光电转塔因光具座结构变形较大所引起的传感器测角误差和多光轴平行度误差超差问题,提出了一种光具座结构改进方案,即将板状结构光具座改为框状结构光具座,并对初始光具座和改进光具座进行了有限元静力仿真分析,通过对比光具座仿真结果和实验验证,表明该光具座结构改进方案是合理的,能够显著提高光具座刚度,有效减少T型光电转塔的测角误差和多光轴平行度误差。

基于子模型的混凝土泵车转台主焊缝强度分析

针对长臂架混凝土泵车转台主焊缝计算结果不准确、计算效率不高的问题,提出基于子模型技术对焊缝进行精细化计算的方法。对转台进行整体计算分析,评估转台主焊缝区域应力;建立转台主焊缝区域的子模型,并在子模型中按照实际参数建立焊缝模型;计算子模型主焊缝在不同网格单元大小下的应力,分析应力收敛性,并验证子模型切割边界的可靠性;优化主焊缝参数,对比优化前后的计算结果,验证优化方案的可行性,并将优化后的参数应用于转台主焊缝的实际生产。结果表明,将子模型技术应用于转台主焊缝的校核与评估,能够显著提高焊缝的计算效率和计算精度,为焊缝参数的优化设计提供科学依据。研究结果为焊缝的设计计算提供了一种可行且有效的方法,也为其它大型构件局部结构的计算提供了重要参考。

舰炮炮塔座圈动态行为与润滑特性

针对舰炮在使用过程中,炮塔座圈经常出现的摩擦磨损问题,通过Adams软件进行动力学仿真,研究了后坐缓冲装置对炮塔座圈接触力的影响。在此基础上,借助FORTRAN编程语言进行弹流润滑分析计算,研究不同环境温度及座圈转速对炮塔座圈润滑性能的影响机制。研究结果表明:安装后坐缓冲装置后,炮塔座圈油膜压力减小而油膜厚度增大;随着转速的增加,油膜压力几乎不变,油膜厚度增大;随着温度的升高,油膜压力变小,油膜厚度变大。揭示了舰炮在特定工作情况下的温度及转速的合理范围,有助于提升舰炮服役性能。