涌升管中的气液两相流研究

发布时间：2018-04-03 03:35

本文选题：涌升管　切入点：气液两相流　出处：《浙江大学》2017年硕士论文

【摘要】：用人工方式将高压气体注入深层海水的垂直提升管中,运用气泡上浮所产生的拖拽力将富含营养盐的深层海水提升至海洋表层,对提高海洋基础生产力有重大意义。该技术领域现有理论较为零散、简单,且在大管径闭式注气系统方面的研究工作尚未有效开展。因此,研究管内水下注气技术中的关键参数如管参数和注气参数等,来分析两相流流型的变化及对提升量的影响就显得尤为重要。本论文的主要内容如下:第一章阐述了本课题的研究目的和意义。分别概述了人工气力上升流和管内气液两相流的研究现状,对两相流流型发展和竖直管内的气液两相流的分类也做了简单的概括。第二章建立及完善了涌升管内注气提升系统的理论模型。本文首次对大管径下的气液两相流进行理论分析,在当前的能量流数学模型基础上增加了含气率参数和提升装备结构所带来的能量损失,重新计算得出了大管径闭式注气系统的提升曲线,同时也对开式、小管径和大管径闭式注气系统在相同注气量情况下的提升量做了比较。第三章研究了涌升管结构参数与液体提升量之间的关系。运用FLUENT进行数值模拟,得到了水下注气提升量随着涌升管的直径、注气口的水下深度和注气流量的增大而增大,随着涌升管长度的增大反而减小,其中,注气量的增加在提高提升量的同时,使提升幅度减小。另外,通过研究管内结构对涌升流流量的影响发现,增加障碍物之后,管内明显形成了强烈的湍流,虽然这使湍流耗散的能量增加了,但同时显著增加了液体的提升量。第四章研究了涌升管中气相含气率对气液两相流流型的影响。通过对涌升管中气液两相流进行数值模拟,在基于网格中含气率过半时即为气相前提下,得出不同流型下两相流含气率对应着不同的波峰值。第五章完成了在涌升管中的水下注气提升实验。实验采用透明有机玻璃管作为提升管,成功观察及测量了在不同涌升管管径、不同进气量和不同的进气深度条件下,两相流流型的形态和变化、管内液体提升量的变化等。第六章总结了对本论文的主要研究工作,并探讨了下一步需要继续的研究工作。
[Abstract]:The high pressure gas was injected into the vertical riser of deep seawater by artificial method, and the drag force generated by bubble floating was used to elevate the deep seawater rich in nutrients to the surface of the ocean, which is of great significance to improve the basic productivity of the ocean.The existing theories in this field are scattered and simple, and the research work on the large diameter closed gas injection system has not been carried out effectively.Therefore, it is very important to study the key parameters, such as pipe parameters and gas injection parameters, to analyze the variation of two-phase flow pattern and its influence on the lifting rate.The main contents of this thesis are as follows: the first chapter describes the purpose and significance of this research.In this paper, the current research status of artificial upward flow and gas-liquid two-phase flow in pipe is summarized, and the development of two-phase flow pattern and the classification of gas-liquid two-phase flow in vertical pipe are also briefly summarized.In the second chapter, the theoretical model of the gas injection system in the riser is established and perfected.In this paper, the gas-liquid two-phase flow in large pipe diameter is theoretically analyzed for the first time. Based on the current mathematical model of energy flow, the loss of energy caused by gas content parameter and lifting equipment structure is increased.The lifting curve of the closed gas injection system with large diameter is calculated and the lifting capacity of the closed gas injection system with large diameter and small diameter is compared with that of the closed injection system with large diameter at the same gas injection rate.In chapter 3, the relationship between the structure parameters and liquid lift is studied.By using FLUENT numerical simulation, it is obtained that the water injection gas lift increases with the diameter of the riser, the underwater depth of the gas injection nozzle and the gas injection flow rate, but decreases with the increase of the riser length.The increase of gas injection increases the lifting amount and decreases the lifting range.In addition, by studying the influence of the structure of the pipe on the upwelling flow, it is found that after increasing the obstruction, a strong turbulence is formed in the pipe, which increases the energy dissipation of the turbulence, but also increases the lift of the liquid.In chapter 4, the influence of gas holdup on the flow pattern of gas-liquid two-phase flow is studied.Based on the numerical simulation of gas-liquid two-phase flow in the riser, on the premise that the gas holdup is gas phase when the gas holdup is over half in the grid, it is obtained that the gas holdup of the two-phase flow in different flow patterns corresponds to different wave peaks.In chapter 5, the lifting experiment of water injection in riser is completed.The transparent plexiglass pipe was used as the riser in the experiment. The shape and change of the flow pattern and the change of the liquid lift in the pipe were observed and measured under the conditions of different riser pipe diameter, different air intake and different intake depth.The sixth chapter summarizes the main research work of this paper, and discusses the further research work.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S95

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