本文選題：氣力人工上升流 + CFD數(shù)值模擬��； 參考：《浙江大學》2017年碩士論文

【摘要】：人工上升流技術(shù)是借鑒自然上升流應運而生的開發(fā)利用海洋資源的新技術(shù),它能將富有營養(yǎng)鹽的深層海水提升到海洋表層,提高海洋表層的初級生產(chǎn)力,增加碳匯,改善海洋環(huán)境等。本文主要針對氣力人工上升流技術(shù)進行數(shù)值模擬研究,研究不同參數(shù)對氣力人工上升流提升流量的影響和深層水體的擴散范圍。提升流量的增加和深層水體擴散范圍的增大對提高海洋表面初級生產(chǎn)力,增加碳匯,改善海洋環(huán)境等具有重要的意義。在已有的氣力人工上升流研究基礎(chǔ)上,研究以下幾個參數(shù)對于氣力人工上升流提升流量的影響。一是研究注氣噴頭的類型,二是研究注氣噴頭的注氣孔數(shù),三是研究注氣深度,四是研究涌升管管型。然后研究兩個參數(shù)對深層水體擴散范圍的影響,一是深層水體從管口噴出的速度,二是涌升管管型。針對以上研究任務,主要運用CFD數(shù)值模擬方法進行研究,工作流程如下。一是對課題組成員曾做過的千島湖試驗進行認真的學習分析,根據(jù)千島湖試驗的情況建立全尺度的涌升管幾何模型和計算域幾何模型,在商業(yè)軟件STAR-CCM+中進行網(wǎng)格劃分并運用VOF方法進行氣力人工上升流的計算模擬。二是驗證計算結(jié)果的正確、可靠性,第一步是網(wǎng)格獨立性驗證,分別用網(wǎng)格數(shù)為105萬、121萬、153萬和189萬四套網(wǎng)格計算不同注氣量下的深層水體提升流量,最終選取網(wǎng)格數(shù)為153萬的作為后續(xù)計算的網(wǎng)格;第二步是用CFD數(shù)值計算所得的深層水體流量去和試驗數(shù)據(jù)作比較,試驗數(shù)據(jù)和數(shù)值計算結(jié)果的趨勢基本相符。三是利用驗證后的CFD數(shù)值模型和網(wǎng)格分別計算不同注氣噴頭類型(十字注氣噴頭和圓環(huán)注氣噴頭),不同注氣孔數(shù)(24孔和384孔)、不同注氣深度(6.1m、9.6m、16.1m)、不同涌升管管型(頂部擴張管和頂部收縮管)情況下的深層水體提升流量。四是針對深層水體擴散范圍的研究重新建立涌升管(等直徑管、頂部擴張管、頂部收縮管)和計算域幾何模型,在商業(yè)軟件STAR-CCM+中進行網(wǎng)格劃分并運用VOF方法計算深層水體的擴散范圍。根據(jù)以上工作流程完成本文,得出如下結(jié)果。一是圓環(huán)注氣噴頭相較于十字注氣噴頭,能更多地提升深層水體。二是注氣孔數(shù)為24孔時,提升的深層水體流量大于注氣孔數(shù)為384孔時。三是隨著注氣深度的增加,深層水體的提升流量也增加。四是頂部擴張管的頂部直徑為0.6m和0.8m時,與等直徑(0.4m直徑)管相比,能更多地提升深層水體,但是當頂部直徑為1.0m時,其提升的深層水體流量反而低于等直徑管;頂部收縮管(頂部直徑分別為0.3m、0.2m、0.15m)提升的深層水體流量不如等直徑管多。五是在等直徑管和頂部擴張管情況下,噴出速度增大,擴散范圍也隨之增大。而在頂部收縮管情況下,隨著噴出速度的增大,擴散范圍基本不變。六是在相同噴出速度的情況下,擴散范圍最大的是頂部擴張管,其次是等直徑管,范圍最小的是頂部收縮管。分析以上的結(jié)果,得出以下結(jié)論:在涌升管的注氣設(shè)計中,如果從靠近涌升管管壁的地方注氣效果會優(yōu)于從涌升管中部注氣;注氣孔數(shù)的多少對應的是注氣孔的大小,也就是氣泡的大小,過小的氣泡并不利于提升深層水體;注氣深度大有利于提升深層水體,但是這會增加工程難度,在實際的氣力人工上升流系統(tǒng)設(shè)計中可以根據(jù)不同的實地情況進行調(diào)整;適當?shù)財U大注氣噴頭以上的涌升管管徑不僅能增加深層水體的提升流量,對于深層水體的擴散也是很有益的。
[Abstract]:Artificial upflow technology is a new technology for exploiting and utilizing marine resources for reference to natural upwelling. It can raise the deep sea water of rich nutrients to the surface of the ocean, improve the primary productivity of the ocean surface, increase the carbon sink and improve the marine environment. This paper is a numerical simulation of the artificial upflow technology. It is of great significance to improve the primary productivity of the ocean surface, increase the carbon sink and improve the marine environment. On the basis of the research on the existing artificial upward flow of the gas force, the increase of the flow rate and the increase of the depth of the deep water body are of great significance to the improvement of the marine surface primary productivity. The first is to study the influence of the following parameters on the flow of the artificial upwelling. One is to study the type of gas injection head, two is to study the number of gas injection holes in the gas injection head, the three is to study the depth of gas injection, and the four is to study the type of piping. Then, the influence of the two parameters on the diffusion range of the deep water body is studied, the first is the velocity of the deep water body ejecting from the pipe mouth. Degree, two is the upwelling tube type. In view of the above research tasks, the main use of CFD numerical simulation method is studied and the work flow is as follows. First, the Qiandao Lake experiment of the team members has been carefully studied and analyzed. According to the situation of the Qiandao Lake test, the full scale upwelling tube geometry model and the computational domain geometric model are set up in the business. In the software STAR-CCM+, the grid is divided and the VOF method is used to simulate the artificial upflow of the air force. Two is to verify the correctness and reliability of the calculation results. The first step is to verify the independence of the grid, and use the grid number of 1 million 50 thousand, 1 million 210 thousand, 1 million 530 thousand and 189 million grids to calculate the flow of the deep water under different gas injection quantities, and the final selection is to be selected. The grid number is 1 million 530 thousand as a follow-up grid. The second step is to compare the flow of deep water with the CFD numerical calculation and the experimental data. The trend of the experimental data is basically consistent with the numerical calculation results. Three is to calculate the different gas injection head types using the verified CFD numerical model and the grid. Ring injection gas injection head), different injection holes (24 holes and 384 holes), different gas injection depth (6.1m, 9.6m, 16.1m), different surge pipe type (top dilated tube and top shrinkage tube) in the deep water body to improve the flow. Four is for the deep water diffusion of the study to reestablish the upwelling pipe (equal diameter pipe, top dilatation tube, top contracting tube) and The computational domain geometry model is used in the commercial software STAR-CCM+ to mesh and use the VOF method to calculate the diffusion range of the deep water body. According to the above work process, the following results are completed. First, the ring injection nozzle can increase the depth of the deep water body more than the cross injection head. Two, when the number of holes is 24 holes, it is raised. The flow rate of deep water body is greater than that of 384 holes. Three is the increase of the depth of water with the increase of gas injection depth. Four when the top diameter of the top tube is 0.6m and 0.8m, it can increase the deep water body more than the equal diameter (0.4m diameter) tube, but it is the deep water flow of its elevation when the diameter of the top is 1.0m. At the top of the contraction tube (the top diameter is 0.3m, 0.2m, 0.15m), the depth of the water flow is less than that of the equal diameter tube. Five is the increase of the ejection velocity and the diffusion range under the condition of the equal diameter tube and the top dilatation tube, and the diffusion range is increased with the increase of the ejection velocity at the top of the retraction tube. Six is basically the same. In the case of the same ejection speed, the largest diffusion range is the top dilatation tube, followed by the equal diameter tube, and the minimum range is the top shrinkage tube. Analysis above results show that in the gas injection design of the upwelling pipe, the effect of gas injection from the vicinity of the upwelling tube wall will be better than that from the middle of the upwelling pipe. The number of gas injection corresponds to the size of the blowhole, which is the size of the bubble, and the small bubbles are not conducive to the promotion of deep water body; the depth of gas injection is beneficial to the promotion of deep water body, but this will increase the difficulty of the engineering, and can be adjusted according to the actual conditions of the actual air force artificial upwelling system. Properly expanding the diameter of the upwelling pipe above the gas injecting nozzle can not only increase the flow rate of the deep water body, but also be beneficial to the diffusion of the deep water body.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P74

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