【作者】 刘碧涛；

【导师】 尤云祥；

【作者基本信息】 上海交通大学 ， 船舶与海洋结构物设计制造， 2011， 硕士

【摘要】 随着陆地和浅海石油资源开采产量的逐步稳定,世界各国均开始将石油资源开采的触角伸向深海海域,与此同时,海洋结构物所面临的海况也将更加恶劣。海洋内波便是其中具有代表性的一种恶劣海况。海洋内波具有振幅大、持续时间长等特点,在特定条件下会对海洋结构物造成巨大的破坏。内孤立波与海洋结构物的相互作用具有很强的非线性,特别是与大长径比挠性部件,如深海立管等,其非线性作用将不可忽略,此时,这类问题将不能再用线性理论来解决。因此,本文采用数值方法来研究内孤立波与深海立管的相互作用,以期为解决这类强非线性问题提供一种可行的解决方法。本文首先回顾和总结了国内外有关内孤立波理论的研究现状。在此基础之上,对内孤立波与深海立管的相互作用问题开展了以下几方面的工作:一,根据内孤立波mKdV理论,以RANS方程为控制方程,结合k ??湍流模型和VOF方法,采用速度入口作为入口边界条件建立了内孤立波数值水槽。二,利用上文所建立的内孤立波数值水槽,研究了内孤立波与大长径比深海立管相互作用时的受力特性,并对立管在内孤立波作用下的受力变化、立管周围流场分布和压力随时间变化的情况进行了显示。三,将内波与立管相互作用得到的时历载荷作为结构有限元软件ABAQUS的时变载荷,采用基于薄壳理论的有限元方法,对深海立管在内孤立波作用下的动力响应特性进行了研究。四,运用基于Morison公式求解内孤立波载荷的工程简化方法,结合考虑内流的细长杆件动力学方程,给出了立管的运动控制方程,并编制有限元程序对方程进行求解,研究了表面波、内孤立波和非均匀海流与顶张紧深海立管相互作用时立管的位移变化情况。研究表明,当内孤立波经过立管时,立管会产生大尺度变形,同时还会在两端产生应力集中现象,所以在实际工程应用中考虑内孤立波对立管的影响是十分必要的。更多还原

【Abstract】 With the constant of the onshore and shallow water oil production, the whole world began to exploit the deep-sea oil. At the same time, the marine structures will face more severe and complicated load, such as the Internal Solitary Wave. The Internal Solitary Wave have the characteristics of single wave, large amplitude, long period and great nonlinear characteristics. It contains vast amounts of energy and sometimes causes great destruction for deep-water structures.Since the interaction between Internal Solitary Wave and the marine structures is high nonlinear, especially for large aspect ratio of flexible components, such as the deep-sea risers, so the linear potential theory will not solve such a problem. In this paper, numerical internal solitary wave flume is established to solve the problem.On the basis of reviewing recent progress of the problem, the works in the thesis are presented as follow:First, based on the mKdV internal solitary wave theory and the RANS equation, with turbulence model and the volume of fluid (VOF) method, a numerical internal solitary waves flume is developed which can generate waves by controlling the velocity of two velocity inlet boundary and absorb waves by use of numerical dissipation.Second, the load characteristics of the interaction between internal solitary waves and large aspect ratio riser were numerically simulated and analyzed by use of the proposed numerical flume. The characteristics of the dynamic load, the velocity and the pressure on the riser due to such an internal solitary wave were presented.Third, deformation and stress characteristics of the deep-sea riser due to the internal solitary waves were simulated and analyzed by use of the finite element method based on the thin shell model. Four, based on the modified Morison formula, combining the dynamic equation of the elastic beam where the effect of the internal flowing fluid is taken into account, a simplified engineering model for analyzing the coupling dynamic response of the riser by surface wave, internal solitary wave and internal flow is presented.The results show that internal solitary wave will give rise to large deformation and stress concentration. Therefore, the influence of internal solitary wave on the deep-sea risers can not be neglected in practical engineering.更多还原