基于实测的导管架下水研究

发布时间：2018-04-21 17:04

本文选题：导管架下水 + 实测　；参考：《上海交通大学》2014年硕士论文

【摘要】：随着我国海洋油气开发的发展，导管架平台的运用越来越普遍，并且所能到达的水深越来越深，导管架的尺度也随之增大。目前大部分的大中型导管架采用驳船运输和滑移下水进行安装，这就导管架对下水过程的设计提出了更高的要求。本文以导管架下水的实型测量为基础，结合模型试验和数值计算，对大型导管下水的过程进行了全面的分析讨论。导管架下水实型测量的内容主要包括两部分：一是下水过程导管架和驳船的运动；二是下水过程中摇臂的受力情况。对于导管架的运动，本文设计了GPS/惯性导航组合系统来进行测量。当导管架处于水面上时，利用精度较高的GPS测量其运动速度，当导管架入水后，GPS失效，利用惯性导航测量导管架加速度；结合姿态矩阵解算导管架和驳船在下水过程中的运动时历。针对驳船摇臂在下水过程中的受力情况，选取可能出现的压力集中点，，设计应力测量方案，利用光纤光栅应变计对导管架下水过程中摇臂受力进行实型测量。实测得出的运动结果表明，整个导管架下水过程持续时间约为80s。期间经历了导管架与驳船只有相对滑动、导管架与摇臂同步旋转、导管架自扶正等阶段。整个过程中导管所能到达的最大潜深约在水面以下80~90m，导管架最大纵摇角度为25°左右。摇臂受力最大的时刻出现在导管架重心滑移到摇臂转轴上方时，此时单个摇臂表面受力大约在6000t~7000t之间。模型试验中，选取不同的初始下水纵倾角，对下水过程进行试验。结果显示，不同的初始下水纵倾角对导管架的运动影响不大，其最大纵摇角随着初始纵倾的增大而略微减小；但是对于驳船而言，初始下水纵倾角越大，在下水过程中其所能达到的最大纵摇角也越大。模型试验得出的导管架纵摇和垂荡时历曲线换算到实型值与实测值对比结果显示，纵摇和垂荡的幅值均符合得较好，而下水过程中各关键时刻的时间节点均有所差别，通过模型试验换算的时间要长于实际测量值，本文分析认为是由于雷诺数的不同引起的。对导管架下水过程的数值模拟计算发现，导管架与滑道间的不同摩擦力系数会对整个运动过程产生比较大的影响，主要体现在各关键时刻的时间节点上。在初始纵倾角、初始船中吃水与摩擦力系数相同的情况下，数值计算得出的垂荡、纵摇等运动幅值均略大于实测值，本文分析认为，这是计算程序中对导管架所受到的附加质量和阻尼估计不足造成的。
[Abstract]:With the development of offshore oil and gas development in China, the application of jacket platform is becoming more and more common, and the depth of water can be reached more and more deeply, and the scale of jacket also increases. At present, most large and medium-sized jacket are installed by barge transportation and slip launching, which puts forward higher requirements for the design of launching process. Based on the real type measurement of jacket launching, combined with model test and numerical calculation, this paper makes a comprehensive analysis and discussion on the launching process of large ducts. There are two parts in the measurement of jacket launching, one is the movement of jacket and barge during launching, the other is the force of rocker arm during launching. The GPS/ inertial navigation integrated system is designed to measure the movement of the jacket. When the jacket is on the surface of the water, the high precision GPS is used to measure the velocity of the jacket, when the jacket enters the water, the GPS fails, and the inertial navigation is used to measure the acceleration of the jacket. The kinematic chronology of jacket and barge during launching is calculated by using attitude matrix. In view of the stress situation of the rocker arm in the launching process, the stress measurement scheme is designed by selecting the possible pressure concentration point, and the actual force of the rocker arm in the launching process of the jacket is measured by using the fiber grating strain gauge. The measured results show that the duration of the whole jacket launching process is about 80 s. During the period of jacket and barge only relative sliding, jacket and rocker arm synchronous rotation, jacket self-leveling and so on. The maximum depth of the conduit is about 80 ~ 90 m below the water surface, and the maximum pitch angle of the jacket is about 25 掳. When the center of gravity of the jacket slips to the top of the shaft of the rocker arm, the single rocker arm surface forces about between 6000t~7000t. In the model test, different initial launching inclination angles are selected to test the launching process. The results show that the maximum pitch angle decreases slightly with the increase of initial pitching, but for barges, the initial launching pitch angle increases with the increase of initial launching pitch angle. The maximum pitch angle can be reached in the launching process. The results of model test show that the amplitudes of pitching and swaying are in good agreement with the measured values, and the time nodes of each critical moment in the launching process are different. The conversion time from the model test is longer than that from the actual measurement value. The analysis shows that it is caused by the difference of Reynolds number. The numerical simulation results show that the different friction coefficients between the jacket and the slide track have a great influence on the whole movement process, which is mainly reflected in the time nodes at each critical moment. When the initial inclination angle, draft and friction coefficient of the initial ship are the same, the amplitude of motion, such as sagging and pitching, obtained by numerical calculation is slightly larger than the measured value. This is due to the insufficient estimation of the additional mass and damping of the jacket in the calculation program.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P751

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