【作者】 刘新立；

【导师】 严仁军；

【作者基本信息】 武汉理工大学 ， 海洋工程结构， 2009， 硕士

【摘要】 船舶液舱晃荡问题已成为载液货船结构设计过程中面临的一个共性问题,尤其是在大型原油货轮(VLCC)、液化石油气船(LPG)及液化天然气船(LNG)等液货船上的开发与应用上表现的尤为突出。晃荡一般发生在船体在波浪中的运动频率与液舱内液体固有振动频率相近的时候,当晃荡发生时,液体将对液舱结构产生强烈的冲击,甚至损坏船体结构。因此,在载液货船的研发设计中,液舱晃荡分析是一项非常重要的研究课题。晃荡问题是一种典型的流固耦合问题,是一种非常复杂的流体运动现象,具有高度的非线性和随机性。影响晃荡的参数有很多,晃荡的剧烈程度与外界的激励频率、舱室的几何形状及尺寸、内部构件、液体充装高度、液体属性等因素有关。本文研究的主要内容是以晃荡分析的数值方法为基础,运用MSC.Dytran程序对一个模型液舱的晃荡情况进行仿真模拟,并探讨不同的液舱内部结构形式及激励频率对晃荡的影响,主要工作内容如下:(1)阐述了分析液体晃荡的三种基本方法:纯理论分析法、数值分析法、实验方法,从流体运动方式的描述、控制方程的离散及自由液面的追踪这三个关键点来详细的阐述了数值分析方法的原理。(2)重点讨论了基于有限体积法的晃荡分析的原理、步骤及相应的特点。采用大型通用有限元程序MSC.Dytran对液舱内液体进行了数值模拟和分析,实现液体晃荡的全过程数值仿真,得到了舱内自由液面运动时间历程及流体对舱壁冲击压力的时间历程图。(3)分析了模型液舱内液体不同装载率水平下的晃荡载荷及自由液面波动图,并与德克萨斯大学所做的摇荡实验结论进行对比,验证了用通用大型有限元程序MSC.Dytran来进行液体晃荡分析的可行性与可靠性。(4)从能量角度分析液体的晃荡并指出制荡舱壁制晃的原理。利用MSC.Dytran分析在同样激励情况下,对内部有障碍物和没有障碍物的两种液舱晃荡进行对比分析;讨论了不同的激励频率对晃荡的影响。并且得出相关结论。更多还原

【Abstract】 Sloshing in tanks is becoming main interest in tank structure design, especially on the development and application of large liquid carries, such as VLCC、LPG and LNG. Generally speaking, sloshing often occurs when the frequency of ship motion in waves coincides with the inherent vibration frequency of the liquid inside the tanks, when sloshing occurs, sloshing causes violent fluid impacts on tank boundary structure with high pressure, and even damage to the hull structure. Therefore, tank sloshing analysis is a very important research topic in the R & D design of liquid carries.Sloshing is a typical problem of fluid and structure coupling and a very complex phenomenon of flow with a high degree of nonlinearity and randomness. The intensity of sloshing depends on many factors, such as frequency of excitation、compartment geometry、internal components、filling ratio and liquid properties. The main contents of this paper is based on numerical methods of sloshing analysis, and simulate sloshing phenomenon of a model tank by use of MSC.Dytran, and discuss the affect of sloshing due to different forms of the internal tank structure .the main jobs of this paper are as follows:(1)Introduce three basic methods of liquid sloshing analysis, purely theoretical analysis, numerical analysis, experimental methods. Elaborate the principal of numerical analysis from the description of fluid movement and the discrete of control equations and the tracking of free surface.(2)The discussion focus on the principal、steps and related characteristics based on the finite volume method. Simulate and analyze the sloshing of liquid in the tank by use of MSC.Dytran, and achieve the goal of whole liquid sloshing process of numerical simulation, and get the time history graphs of free surface motion and pressure on the ship hull due to fluid impact.(3)Analyze the sloshing load and free surface fluctuation of liquid in the model tank under different filling ratio and compare with relevant experimental results. Draw the conclusion that it is feasible to analyze the liquid sloshing by use of MSC.Dytran.(4)Analyze the energy of liquid sloshing from the energy point of view and point out the principal of suppression sloshing by use of barricade. Analyze the liquid sloshing with or without barricade under the same incentive circumstances and draw the relevant conclusion.更多还原