管道气液两相流流型及热—流—固耦合数值模拟研究

发布时间：2018-05-06 10:22

本文选题：CFD + 气液两相流　；参考：《长江大学》2015年硕士论文

【摘要】：在油气生产领域,油、气、水通常是从油井同时产出,并以气液两相的形式进行长距离输送。在管道气液两相的流动过程中,当输送管道系统内为多相流动时,流体的速度和压力不断变化,产生不稳定流动和变形(或运动),这种不稳定流动对管道变形的变形产生很大影响会导致管道系统的损坏。因此,针对管道系统的热-流-固耦合特性进行的深入研究具有广泛的工程背景和现实意义。本文从数值模拟角度对油气管道两相流流型、管道-地层温度场、流场与管道壁之间的热-流-固耦合情况进行了数值预测研究。本文首先采用VOF多相流模型和标准k-e模型湍流模型对水平管道、铅直管道和夹角60°的倾斜管道内常见的几种流型进行了数值计算和分析。模拟结果表明：建立的二维模型可再现Baker流型图关于水平管道中常见的7种流型,即弥散泡状流、泡状流、活塞流、段塞流、环状流、层流和波浪流,模拟结果与三维模型比较发现两种模型下流型模拟结果差异性较小；数值模拟结果同时再现了Taitel流型图关于铅直管和倾斜管中常见的5种流型,即弥散泡状流、泡状流、段塞流和环状流,流型预测达到预期效果,并对倾斜管中气、液相流量的变化对倾斜管道内流型的影响进行了研究。此外,将112组不同角度下的流型模拟结果与Taitel流型图进行对比,得到以下结论：在管道流型的数值模拟中,如若不考虑气体的可压缩性,在气相折算速度特别大的情况下管道内只会出现环状流一种流型,如需进行气相折算速度较大时的流型模拟,需要对模型进行修正；气液两相流在自下而上倾斜角度较大或者近似铅直的管道中经常会呈现段塞流,对这种管道进行段塞流的特定研究具有十分重要的意义；管道倾角的变化会对管内可能出现的流型产生了较为明显的影响；在倾斜管道的数值模拟中频繁出现了雾状流这种流型,这种流型在Taitel流型图中是没有的,而在倾斜管道对雾状流研究中却不可忽略。论文进而对某集输管道进行了模拟研究,整个管路由三段水平管路(L1,L3,L5),两段倾斜管路(L2,L4)和一段垂直管路组成,管长9.1 m,内径0.06m,壁厚0.007m。在本研究中,首先采用FLUENT软件对管道埋地部分进行温度场数值预测,对管道的最优埋地深度进行优化并解算得出管道埋地敷设情况下冬夏两季的管道壁面温度。研究结果表明,在不同季节温度条件下管道周围土壤温度场分布差异很大,有保温层情况将比不带保温层的受影响范围减少50%-90%,该段管道的最优埋地深度是1.2m(存在冻土层),冬夏两季的管道外壁面温度的模拟结果分别为12℃和31℃。在管道-地层温度场数值模拟结果的基础上采用ANSYS Workbench模块进行管道的热-流-固耦合分析。采用FLUENT软件解算得到气液两相在集输管道内不同时刻的两相分布、界面变化和沿程压降,并结合集输管道各拐角及特定截面处的气相体积分数云图和速度曲线图对管内流型进行了特定分析。结果表明：不同管段分别出现了分层流、波浪流、气泡流、段塞流和环状流等多种流型,气液两相流在流经水平段进入倾斜向上管路或者垂直向上管路时,在拐角处最容易产生积液；在管道90°弯管处容易出现较大漩涡。将流体对管道内壁面的压力载荷、管道体上的温度载荷加载到管道上,同时对管道进行固定约束,解算得到管道固体壁面的最大位移量、等效应力和等效应变。结果表明：管道的管材、壁面温度和管内流量的变化都会对长输管道的变形位置、变形大小和等效应力、应变产生影响,温度载荷和气液量变化产生的影响较为明显。
[Abstract]:In the field of oil and gas production, oil, gas and water are usually produced at the same time from the oil well and are transported in a long distance in the form of gas-liquid two phases. In the process of gas and liquid two-phase flow in the pipeline, when the pipeline system is multiphase flow, the velocity and pressure of the fluid are constantly changing, resulting in unstable flow and deformation (or motion), such unstable flow, The deformation of the pipeline has a great influence on the damage of the pipeline system. Therefore, the deep research on the thermal fluid solid coupling characteristics of the pipeline system has extensive engineering background and practical significance. The heat of the two phase flow, the temperature field of the pipeline formation and the heat between the flow field and the wall of the pipeline from the numerical simulation point of view. The numerical prediction study of the fluid solid coupling situation is carried out. Firstly, the VOF multiphase flow model and the standard k-e model turbulence model are used to calculate and analyze several common flow patterns in the horizontal pipe, the plumbing pipe and the inclined pipe with the angle of 60 degrees. The simulation results show that the established two-dimensional model can be reproduced by the Baker flow pattern about water. 7 common flow patterns in flat pipes, namely, dispersion bubble flow, bubble flow, piston flow, slug flow, annular flow, laminar flow and wave flow, are compared with the three-dimensional model. The results of the two models are less different, and the results of numerical simulation reproduce the 5 common flow patterns of the Taitel flow pattern on the plumbing and the inclined tube. Diffusion bubble flow, bubbly flow, slug flow and annular flow, flow pattern prediction reached the expected effect, and the influence of the change of gas and liquid flow in the inclined pipe on the internal flow pattern of the inclined pipe was studied. In addition, the flow pattern simulation results under 112 groups of different angles were compared with the Taitel flow pattern, and the following conclusions were obtained: the number of flow patterns in the pipeline In the value simulation, if the compressibility of gas is not considered, there is only a circular flow pattern in the pipe in the case of high gas phase conversion speed. If the flow pattern is simulated with high gas phase conversion speed, it is necessary to modify the model. The gas and liquid two phase flow is in a large or nearly straight pipeline. The slug flow is often presented, which is of great significance to the specific study of the slug flow in this kind of pipeline. The change in the dip angle of the pipe will have a more obvious effect on the possible flow pattern in the tube; the flow pattern of the foggy flow appears frequently in the numerical simulation of the inclined pipe, and this flow pattern is not in the Taitel flow pattern. It is not negligible in the study of the foggy flow in the inclined pipeline. The paper then simulated the pipeline of a certain gathering pipeline. The whole pipe route is composed of three segments (L1, L3, L5), two segments (L2, L4) and a vertical line, the length of the pipe is 9.1 m, the inner diameter 0.06m, and the wall thickness 0.007m. in this study, the pipeline is first buried by the FLUENT software. The ground part carries out the numerical prediction of the temperature field, optimizes the optimal buried depth of the pipeline and calculates the wall temperature of the pipeline in the two quarter of winter and summer in the pipeline buried. The results show that the distribution of soil temperature field around the pipeline is very different under different seasonal temperature conditions, and the condition of the insulation layer will be more than that without the insulation layer. The optimum burying range is 50%-90%, and the optimal buried depth of the pipeline is 1.2m (frozen soil layer). The simulation results of the outer wall temperature of the pipeline in the two quarter of winter and summer are 12 and 31, respectively. On the basis of the numerical simulation results of the pipe formation temperature field, the ANSYS Workbench module is used to analyze the heat flow solid coupling analysis of the pipes. The FLUENT software solution is used. The two phase distribution of gas and liquid two phases in the gathering pipeline, the interface change and the pressure drop along the path are calculated, and the internal flow pattern of the pipe is analyzed with the gas phase volume fraction and velocity curves at the corner of the gathering pipeline and the specific cross section. The results show that the stratified flow, wave flow and bubble flow appear in the different pipe segments, respectively. In a variety of flow patterns, such as slug flow and annular flow, when the gas and liquid two phase flow enters the inclined upward pipe or vertical upward pipeline through the horizontal section, it is the most easy to produce the fluid at the corner, and the larger whirlpool is easy to appear at the 90 degree bend pipe of the pipeline. The maximum displacement, equivalent stress and equivalent strain of the pipe solid wall are obtained by the fixed constraint on the pipe. The results show that the pipe material, the wall temperature and the flow in the tube will affect the deformation position, the deformation size and the equivalent stress, the stress and the change of the temperature load and the gas and liquid quantity. The influence is more obvious.

【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE832

【参考文献】