波流联合作用下海洋立管载荷与响应分析

发布时间：2018-01-26 18:09

本文关键词： 立管波流联合作用数值水池载荷响应流固耦合　出处：《江苏科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着深海资源开发领域的不断拓展,海洋立管等结构物在波流等外载荷下的运动响应问题越来越受到人们的关注。本文在较为全面地回顾和总结了国内外数值水池和海洋立管载荷响应研究方法和最新进展的基础上,基于时域方法和粘流理论,以不可压缩流体连续方程、N-S方程和结构动力学方程为基本控制方程,借助商用软件平台Ansys Workbench14.5,构建了粘性数值水池,针对海洋立管的载荷响应问题开展了以下研究工作并得到了相应结论:(1)基于商用软件FLUENT 14.5,结合软件自定义函数(UDF)功能,采用速度边界造波法和阻尼消波技术,通过VOF追踪自由液面,建立了精度良好的二维和三维数值波浪、波流数值水池。分析了不同波流参数联合作用下数值水池的波浪参数变化,得到了波流同向时,波长变长,波幅减小;波流相向时,波长变小,波幅增加的结论。(2)在完成数值水池构造的基础上,建立了刚性海洋立管模型,对其在波流共同作用下所受载荷进行了仿真模拟。通过表面压力和水平的作用力的分析,发现立管在波流同向中受力增加,且水平作用力系数增大;波流相向时,立管表面压力减小,水平作用力系数降低。(3)采用双向耦合分离法思想,通过流固耦合模块System Coupling将流域和结构域计算数据交互传递,对长径比为8的柔性立管在数值水池中的运动响应进行了双向流固耦合模拟。结果分析表明,相对单独波浪场中,立管在波流数值水池中迎浪向振动平衡位置偏向水流方向,横浪向振幅显著增大,轴向振动变化不大。同时通过文献对比和水平作用力系数的分析验证了所用方法进行流固耦合模拟的可行性。(4)数值模拟了长径比为103的柔性立管在数值水池中的运动响应。模拟结果表明波流作用对大长径比的作用效果更为显著,迎浪向振动平衡位置较单独波浪场中向水流方向偏移,横浪向出现明显往复振动。波流同向时,立管运动振幅增大,整体受力下移;波流相向时,振幅减小,整体受力上移。
[Abstract]:Along with the deep sea resources development domain unceasing expansion. More and more attention has been paid to the motion response of marine risers and other structures under external loads such as waves and currents. In this paper, the research methods of load response of numerical pools and risers at home and abroad are reviewed and summarized. On the basis of new developments. Based on the time-domain method and the viscous flow theory, the incompressible fluid continuity equations (N-S) and structural dynamics equations are taken as the basic governing equations. With the help of the commercial software platform Ansys Workbench 14.5, the viscous numerical water pool is constructed. The following research work has been done on the load response of marine riser and the corresponding conclusion: 1) based on the commercial software FLUENT 14.5and combined with the function of software custom function. Two and three dimensional numerical waves with good accuracy are established by means of velocity boundary method and damped wave elimination technique. The free liquid surface is tracked by VOF. The variation of wave parameters under the combined action of different wave and current parameters is analyzed, and the wave length and amplitude are obtained when the wave and current are in the same direction. The conclusion that the wave length becomes smaller and the wave amplitude increases when the wave current is in the opposite direction. (2) on the basis of completing the construction of the numerical pool, the rigid ocean riser model is established. Through the analysis of surface pressure and horizontal force, it is found that the force of riser increases in the same direction of wave and current, and the coefficient of horizontal force increases. When the wave and current are opposite, the surface pressure of riser decreases and the coefficient of horizontal force decreases. 3) the bidirectional coupling separation method is adopted. The fluid-solid coupling module (System Coupling) is used to transfer the data between the basin and the domain. The motion response of flexible riser with aspect ratio of 8 in a numerical pool is simulated by two-way fluid-solid coupling. The results show that the response of the flexible riser in a single wave field is higher than that in a single wave field. The balance position of the riser in the wave-current numerical pool is inclined to the direction of the flow, and the amplitude of the transverse wave increases significantly. The axial vibration has little change, and the feasibility of fluid-solid coupling simulation is verified by the comparison of literature and the analysis of horizontal force coefficient. The motion response of flexible riser with a aspect ratio of 103 is numerically simulated in a numerical pool. The simulation results show that the effect of wave-current action on large aspect ratio is more significant. The equilibrium position of facing wave direction vibration is more than that of single wave field, and the transverse wave direction appears reciprocating vibration obviously. When the wave current is in the same direction, the amplitude of riser motion increases and the whole force moves downward. When the wave and current are opposite, the amplitude decreases and the whole force moves up.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P75

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