旁靠浮式结构间窄缝水动力振荡研究

发布时间：2018-11-09 12:15

【摘要】：海上油气开采及输送中,通常遇到旁靠多浮式结构协同作业的问题。在某些海况下,多浮式结构之间会出现严重影响海上作业安全性和稳定性的强耦合作用情况。本文基于粘流理论以及计算流体力学(CFD)理论,自由液面捕捉采用VOF法,基于CFD商业软件Flow3D,对两浮式结构窄缝间的流场问题进行了详细分析,以研究窄缝水波振荡现象的规律。论文的主要工作成果如下:(1)详细介绍了常见的旁靠多浮体系统,并对国内外关于多浮体水动力干扰的研究现状进行了较为全面的综述,对各类研究方法和应用进行了归纳和总结。(2)建立了旁靠浮式结构相互耦合作用分析模型,通过二维和三维数值波浪水槽,对窄缝间的流场进行了数值计算。计算结果与有关文献中的试验结果较为一致,验证了本文研究方法和数值计算的准确性和可靠性。(3)首先对旁靠模型进行网格收敛性分析,选择最优网格划分方案,计算分析了两固定结构物窄缝间的流场问题。通过对波面升高和窄缝间流体运动两方面的分析,发现:当窄缝间距相同时,不同波浪周期下窄缝间的流体运动各不相同,当入射规则波达到共振周期时,窄缝间流场会出现显著的波浪升高现象;随着窄缝间距的增大,窄缝间流场的共振周期也随之增大。当波长过大时,窄缝对内外流场起到遮蔽效应,窄缝间不会出现明显的波面升高。当波长进一步减小,小于1倍船长时,波浪可以进入窄缝内部并出现波面升高,此时窄缝间距越小,窄缝间流体的运动越剧烈。窄缝间可有一个或多个峰值点,其与长宽比L/B和波长比λ/L有关。(4)数值分析了波浪/多浮体运动/窄缝振荡的全耦合问题。通过比较单浮体和多浮体在运动和受力上的差异发现:由于窄缝间流体运动的影响,自由浮式结构的运动和受力发生较大幅度的变化,说明窄缝间流体运动对结构的影响是不可忽略的。(5)通过改变波浪的入射方向,对斜浪和横浪作用下,两浮式结构窄缝间的流场问题进行了数值模拟,分析横浪与斜浪作用下流场的波面升高,窄缝内部的流体运动。并结合迎浪计算的结果,对比分析三种浪向下浮体的运动与受力情况,得出斜浪相较于其他工况更为危险的结论。
[Abstract]:In offshore oil and gas production and transportation, the problem of multi-floating structures is usually encountered. Under some sea conditions, there is a strong coupling between multi-floating structures which seriously affects the safety and stability of offshore operations. Based on viscous flow theory and (CFD) theory of computational fluid dynamics, VOF method is used to capture free liquid surface, and the flow field between two floating structures is analyzed in detail based on CFD commercial software Flow3D,. In order to study the law of narrow slit water wave oscillation. The main results of this paper are as follows: (1) the paper introduces the common side floating body system in detail, and summarizes the research status of multi-floating body hydrodynamic disturbance at home and abroad. All kinds of research methods and applications are summarized and summarized. (2) the coupling analysis model of side floating structures is established, and the flow field between narrow slits is numerically calculated by two and three dimensional numerical wave flume. The calculated results are consistent with the experimental results in related literatures, which verify the accuracy and reliability of the research method and numerical calculation in this paper. (3) the mesh convergence analysis of the side model is carried out first, and the optimal mesh generation scheme is selected. The flow field between the narrow slits of two fixed structures is calculated and analyzed. Through the analysis of wave surface rise and fluid motion between narrow slits, it is found that the fluid motion between narrow slits is different under different wave periods when the gap spacing is the same, and when the incident regular wave reaches the resonance period, The phenomenon of wave rising in the narrow gap flow field is obvious. With the increase of the gap spacing, the resonance period of the flow field between the narrow slits increases. When the wavelength is too large, the narrow gap has a shielding effect on the internal and external flow field, and there is no obvious wave surface rise between the narrow gaps. When the wavelength is further reduced to less than 1 times of the captain, the wave can enter the narrow slot and increase the wave surface. The smaller the gap is, the more violent the movement of the fluid between the narrow slits is. There can be one or more peaks between narrow slits, which are related to the aspect ratio L / B and the wavelength ratio 位 / L. (4) the fully coupled problem of wave / multi floating body motion / narrow slit oscillation is numerically analyzed. By comparing the movement and force of single floating body and multi floating body, it is found that the movement and force of free floating structure change greatly due to the effect of fluid movement between narrow slits. It shows that the influence of fluid motion between narrow slits on the structure can not be ignored. (5) by changing the incident direction of waves, the flow field between two floating structures under the action of oblique and transverse waves is numerically simulated. The wave surface rising and the fluid movement in the narrow slot are analyzed under the action of transverse wave and oblique wave. Combined with the results of wave welcome calculation, the movement and force of three kinds of wave downward floating body are compared and analyzed, and the conclusion that oblique wave is more dangerous than other working conditions is obtained.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE95

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