本文選題：涌升管　切入點：氣液兩相流　出處：《浙江大學(xué)》2017年碩士論文

【摘要】：用人工方式將高壓氣體注入深層海水的垂直提升管中,運用氣泡上浮所產(chǎn)生的拖拽力將富含營養(yǎng)鹽的深層海水提升至海洋表層,對提高海洋基礎(chǔ)生產(chǎn)力有重大意義。該技術(shù)領(lǐng)域現(xiàn)有理論較為零散、簡單,且在大管徑閉式注氣系統(tǒng)方面的研究工作尚未有效開展。因此,研究管內(nèi)水下注氣技術(shù)中的關(guān)鍵參數(shù)如管參數(shù)和注氣參數(shù)等,來分析兩相流流型的變化及對提升量的影響就顯得尤為重要。本論文的主要內(nèi)容如下:第一章闡述了本課題的研究目的和意義。分別概述了人工氣力上升流和管內(nèi)氣液兩相流的研究現(xiàn)狀,對兩相流流型發(fā)展和豎直管內(nèi)的氣液兩相流的分類也做了簡單的概括。第二章建立及完善了涌升管內(nèi)注氣提升系統(tǒng)的理論模型。本文首次對大管徑下的氣液兩相流進(jìn)行理論分析,在當(dāng)前的能量流數(shù)學(xué)模型基礎(chǔ)上增加了含氣率參數(shù)和提升裝備結(jié)構(gòu)所帶來的能量損失,重新計算得出了大管徑閉式注氣系統(tǒng)的提升曲線,同時也對開式、小管徑和大管徑閉式注氣系統(tǒng)在相同注氣量情況下的提升量做了比較。第三章研究了涌升管結(jié)構(gòu)參數(shù)與液體提升量之間的關(guān)系。運用FLUENT進(jìn)行數(shù)值模擬,得到了水下注氣提升量隨著涌升管的直徑、注氣口的水下深度和注氣流量的增大而增大,隨著涌升管長度的增大反而減小,其中,注氣量的增加在提高提升量的同時,使提升幅度減小。另外,通過研究管內(nèi)結(jié)構(gòu)對涌升流流量的影響發(fā)現(xiàn),增加障礙物之后,管內(nèi)明顯形成了強(qiáng)烈的湍流,雖然這使湍流耗散的能量增加了,但同時顯著增加了液體的提升量。第四章研究了涌升管中氣相含氣率對氣液兩相流流型的影響。通過對涌升管中氣液兩相流進(jìn)行數(shù)值模擬,在基于網(wǎng)格中含氣率過半時即為氣相前提下,得出不同流型下兩相流含氣率對應(yīng)著不同的波峰值。第五章完成了在涌升管中的水下注氣提升實驗。實驗采用透明有機(jī)玻璃管作為提升管,成功觀察及測量了在不同涌升管管徑、不同進(jìn)氣量和不同的進(jìn)氣深度條件下,兩相流流型的形態(tài)和變化、管內(nèi)液體提升量的變化等。第六章總結(jié)了對本論文的主要研究工作,并探討了下一步需要繼續(xù)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.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S95

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