动力贯入锚水中自由下落过程的数值模拟

发布时间：2018-09-06 14:09

【摘要】：海洋油气开发对保证我国能源需求,实现经济和社会的可持续发展具有重要的战略意义。系泊系统作为浮式海洋开采平台的重要组成部分,对保证平台的安全运行起到了关键性作用。在众多类型的锚固基础中,动力贯入锚的安装操作简便快捷,只需在自重作用下完成在水中的自由下落过程,并贯入海床地基中,具有较高的抗拔承载能力,是近年来深海采油平台发展较快、更适合深水领域的锚固基础。自提出动力贯入锚这一概念,针对动力锚在水中自由下落过程的水动力分析的研究相对较少,故研究其下落过程的水力学特性有着重要的理论意义和实际应用价值。本文采用有限元法,利用FLUENT流体计算力学软件、流体力学理论对动力贯入锚的水中自由下落过程进行了数值模拟,以期对实际深海油气开采所用的锚固基础的设计安装提供依据,研究内容如下：(1)运用流体力学的基本理论以及FLUENT模型理论,如连续性方程,动量方程,边界层与绕流的概念、动网格模型等,对动力锚水中自由下落过程进行动力分析,推导出基本的运动微分方程,确定模拟计算所需要的模型,通过模拟钢球的水中自由下落运动,验证本文中所用模型、方法的正确性。(2)建立鱼雷锚水中自由下落过程的模型,在同一流域模型下,采用三组不同网格细化程度的工况,研究网格细化、边界层划分方法对计算结果的影响,阻力系数随雷诺数的变化,以及在稳定加速度阶段的阻力系数的值,并与已有的文献和实验结果对比分析。(3)建立板翼动力锚水中自由下落过程的模型,在同一流域模型下,采用三组锚体具有不同几何形状的工况进行数值模拟,重点研究加载臂对冲击速度、位移、转角、定向稳定性以及阻力系数的影响；阻力系数与终端速度的关系；给定阻力系数后预测板翼动力锚的速度、位移与时间的关系曲线。
[Abstract]:The development of offshore oil and gas has important strategic significance to ensure the energy demand of our country and realize the sustainable development of economy and society. As an important part of floating offshore mining platform, mooring system plays a key role in ensuring the safe operation of the platform. In many kinds of anchoring foundations, the installation of dynamic penetration anchors is simple and fast, and only need to complete the free fall process in water under the action of self-weight, and penetrate into the foundation of the seabed, so it has higher uplift bearing capacity. In recent years, the deep-sea oil recovery platform has developed rapidly and is more suitable for the Anchorage foundation in the deep water field. Since the concept of dynamic penetration anchor is put forward, there are few researches on hydrodynamic analysis of the free falling process of dynamic anchor in water, so it is of great theoretical significance and practical application value to study the hydrodynamic characteristics of the falling process. In this paper, using the finite element method and FLUENT fluid Computational Mechanics software, the hydrodynamics theory is used to numerically simulate the free falling process of the dynamic penetrating anchor in water. The research contents are as follows: (1) the basic theory of fluid mechanics and the theory of FLUENT model, such as continuity equation, momentum equation, boundary layer and flow around, are used to provide the basis for the design and installation of the anchor foundation used in the actual deep-sea oil and gas exploitation. The dynamic mesh model is used to analyze the free falling process of the dynamic anchor in water, and the basic differential equation of motion is deduced. The model needed for the simulation calculation is determined, and the free falling motion of the steel ball in the water is simulated by simulating the free falling motion of the steel ball. Verify the correctness of the model and method used in this paper. (2) establish the model of the free fall process of torpedo anchor water. Under the same watershed model, three groups of different mesh refinement working conditions are used to study the mesh refinement. The influence of boundary layer partition method on the calculation results, the variation of drag coefficient with Reynolds number, and the value of resistance coefficient at the stage of steady acceleration, The results are compared with the existing literatures and experimental results. (3) the model of the free falling process of the plate-wing dynamic anchor in water is established, and three groups of anchors with different geometric shapes are numerically simulated under the same watershed model. The effects of loading arm on impact velocity, displacement, rotation angle, directional stability and resistance coefficient, the relationship between resistance coefficient and terminal velocity, and the relationship between velocity, displacement and time of dynamic anchor are predicted.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE95

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