海底管线溢油输移过程的数值模拟

发布时间：2018-05-04 19:17

本文选题：水下溢油 + 数值模拟　；参考：《大连理工大学》2015年硕士论文

【摘要】：由于全球对石油能源需求量逐日递增和海上勘探、开采规模不断扩大,海上溢油事故,包括油轮倾覆、海底井喷、输油管道渗漏等屡见不鲜,对海洋生态环境的影响是恶劣且难以消除的。在溢油事故的预测和应急处理研究过程中,除卫星、雷达以及微波等遥感技术的监测预报以外,计算机模拟以其强大的数据处理能力,对相关因素的综合考虑,在溢油事故应急行动中发挥着日益重要的作用。在溢油事故的预测和应急处理研究中,以往注意力多集中在海底管道破坏或油田的井喷造成的大量溢油的情况。本文重点关注海底管道出现破裂等问题而产生蠕孔溢油的水下运动轨迹和影响范围。此类溢油由于其隐蔽性和长期性也会造成较严重的后果。本文基于CFD通用软件FLUENT,采用标准k-ε紊流模型,基于压力的求解器(Pressure-Based Solver)和压力速度耦合的PISO算法,采用VOF追踪相界面,考虑了纯流和纯波作用,建立了二维的海底管线微孔溢油数值模型。在纯横向水流环境下,给出溢油水下运动轨迹数值结果,和前人实验值吻合较好。引入无量纲密度弗劳德数Fr0和溢油出口速率与流体流动速率的比值R0来探讨影响溢油输运过程的因素。比较了Fr0和R0值不同时,溢油初期上升的高度,产生的涡旋,溢油轨迹的弯曲,油体水下漂移距离,浮上水面的位置和时间等变化情况。由分析知当溢油流速和周围水流流速相差不大,油品较重时,溢油上浮到海面时间更长,污染范围更广,寻找、封堵溢油口和清理油污的工作量及难度加大。在纯波浪环境下,模拟了不同波陡kA的波浪环境和静水环境溢油的水下运动形态、流场和水面输运情况。发现静水中溢油在靠近水面前油柱几乎垂直上升,到达水面附近油前端才略有摆动,同时随溢油上浮有对称涡旋现象。油在水面关于溢油口对称输运。而波浪环境中溢油轨迹从开始的垂直上浮很快变为呈S型摆动上升,且随油运动产生的涡旋场更加复杂,溢油在水面的输运也不再关于溢油口对称。波陡kA越大,溢油柱越早受到扰动,轨迹摆动幅度越大,对称涡旋情形越难维持。引入溢油在水面输运影响范围的概念和指标f来表征不同波陡kA对溢油水面输运相对于溢油口的非对称性的影响,数据分析后表明波陡kA越大,波浪非线性越强,溢油的影响范围越向右偏移,即溢油顺波方向的输运越强。
[Abstract]:As the global demand for oil energy increases day by day and offshore exploration, the scale of exploitation continues to expand, the oil spill accidents on the sea, including oil tanker overturning, seabed blowout, and oil pipeline leakage are common, and the impact on the marine environment is bad and difficult to eliminate. In the process of prediction and emergency treatment of oil spill accidents, the satellite, Besides the monitoring and forecasting of remote sensing technology such as radar and microwave, computer simulation plays an increasingly important role in the emergency action of oil spill accident, with its powerful data processing ability and comprehensive consideration of related factors. In the study of oil spill accident prediction and emergency treatment, attention has been focused on submarine pipeline destruction or oil field. A lot of oil spill caused by blowout. This article focuses on the underwater trajectory and influence range of the creeping oil spills. This kind of oil spill will result in serious consequences due to its concealment and long term. Based on the CFD general software FLUENT, the standard k- e turbulence model is used, based on the pressure. The Solver (Pressure-Based Solver) and the pressure velocity coupling PISO algorithm, using the VOF tracking phase interface and considering the pure current and pure wave action, have established a two-dimensional numerical model of the microporous oil spillage in the submarine pipeline. In the pure transverse flow environment, the results of the number of underwater moving trajectories of the spilled oil are given, which is in good agreement with the previous experimental values. The density Froude number Fr0 and the ratio of the flow rate of the spilled oil to the fluid flow rate R0 are used to discuss the factors affecting the transport process of the oil spilled oil. Compared with the difference between the Fr0 and R0 values, the height of the initial rising of the oil spill, the generated vortex, the curve of the oil spill path, the drift distance of the oil body, the position and time of the floating surface and so on. There is little difference between the flow velocity of the oil spilled and the flow velocity in the surrounding water. When the oil is heavier, the oil spill is floating to the sea for a longer time, and the pollution range is wider. The work and difficulty of blocking the oil spill and cleaning the oil are more difficult. In the pure wave environment, the wave environment of different wave steep kA and the underwater movement form of the oil spill in the hydrostatic environment, the flow field and the water surface are simulated. It is found that the oil spillage in the hydrostatic water almost vertically rises before the oil column near the water surface, and the oil front-end near the surface of the water is slightly swinging, while the oil spill has symmetrical vortices. The vortex field produced by motion is more complex, and the transport of oil spill on the surface of the water is no longer symmetrical. The larger the kA is, the earlier the oil spilled column is disturbed, the greater the swing amplitude is, the more difficult the symmetry vortex is to be maintained. The concept of the influence range of the oil spill in the water surface and the reference standard f to characterize the transport of the different wave steepness kA to the oil spilled water surface With the influence of the asymmetry of the oil spill, the data analysis shows that the greater the wave steepness kA is, the stronger the wave nonlinearity is, the more the influence range of the spilled oil moves to the right, that is, the better the transport of the spilled oil is in the direction of the wave.

【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】：X55

【参考文献】