本文選題：并聯(lián)管道　切入點：層流　出處：《蘭州交通大學》2014年碩士論文

【摘要】：常見流體在多分支并聯(lián)管道中的流量分配問題具有極其廣泛的工程應用背景，其中U型和Z型結構為實際工程應用中常見的兩種經(jīng)典并聯(lián)管道模型。這兩種多分支并聯(lián)管道形式是石油化工、火電、鍋爐、太陽能、核電、制冷等領域常用的重要流量分配裝置。流體工質(zhì)在此類并聯(lián)管道中的流動狀況（如流速、流量分配等）直接關系到設備的安全可靠性和經(jīng)濟性。從而，如何設計合理的管道系統(tǒng)來實現(xiàn)流量的均勻分配非常重要。為此，本文采用數(shù)值分析的方法對不同進出口壓差及不同管道幾何參數(shù)條件下并聯(lián)管道系統(tǒng)內(nèi)流體的流動特性進行了研究。 論文研究內(nèi)容有：建立并聯(lián)管道系統(tǒng)的流動模型；對所研究的并聯(lián)管道區(qū)域進行離散；發(fā)展同位網(wǎng)格下已知壓力邊界條件的SIMPLE算法；計算在不同并聯(lián)管道進出口壓力差，不同集管管徑條件下，管道系統(tǒng)的流動特性；進而對流動特性用常用的參數(shù)進行了表示，如軸向動量恢復系數(shù)，側向動量修正系數(shù)，壓降以及并聯(lián)支管進出口處的軸向速度率。 結果表明，并聯(lián)管道系統(tǒng)進出口壓力差的變化對流量分配產(chǎn)生了一定影響，集管管徑的變化給流量分配產(chǎn)生了較大的影響；在一定的條件下，若想獲得較好的流量分配，可以盡可能增大集管管徑。對流動特性采用軸向動量恢復系數(shù)、側向動量修正系數(shù)、軸向速度率、局部阻力系數(shù)、沿程阻力系數(shù)等進行了表征后發(fā)現(xiàn)：軸向動量恢復系數(shù)在分流集管中是波動增加的，在匯集集管中是逐漸減小的；前九個支管進口處的側向動量恢復系數(shù)在是逐漸增大的，第十個支管進口處出現(xiàn)了下降的情況，各并聯(lián)支管出口處的側向動量恢復系數(shù)呈現(xiàn)出先增大后減小的趨勢；對于并聯(lián)支管進出口處的軸向速度率，其變化規(guī)律與側向動量恢復系數(shù)的變化規(guī)律基本上相同，只是在數(shù)值大小是有差別；對于局部阻力系數(shù)的研究，鑒于實際情況，從能量守恒的角度對其進行了定義，數(shù)值結果表明分流集管中每段管道部分的局部損失沿流動方向是逐漸增加的，，匯集集管中是逐漸減小的；各并聯(lián)支管中的沿程損失在靠近支管進口處變化比較劇烈，待流體通過渦流區(qū)后，隨著流體的充分發(fā)展，其沿程損失變化趨一常值。研究結果還提供了一種可直接求解三維并聯(lián)管道系統(tǒng)流體流動特性的數(shù)值方法，為工業(yè)應用的前期設計提供有效的方法。
[Abstract]:The flow distribution problem of common fluid in multi-branch parallel pipeline has a very wide engineering application background. U type and Z type are two typical parallel pipeline models which are common in practical engineering applications. These two kinds of multi-branch parallel pipeline forms are petrochemical, thermal power, boiler, solar energy, nuclear power, The flow condition (such as velocity, flow distribution, etc.) of fluid in parallel pipeline is directly related to the safety, reliability and economy of the equipment. It is very important to design a reasonable pipeline system to realize the uniform flow distribution. In this paper, the flow characteristics of fluid in a parallel pipeline system under different inlet and outlet pressure differences and different geometric parameters are studied by numerical analysis. The main contents of this paper are as follows: establish the flow model of parallel pipeline system; discrete the studied parallel pipeline region; develop the SIMPLE algorithm of known pressure boundary conditions under the same grid; calculate the pressure difference between the inlet and outlet of different parallel pipelines. The flow characteristics of the pipeline system under different pipe-collecting diameters are represented by common parameters, such as axial momentum recovery coefficient, lateral momentum correction coefficient, pressure drop and axial velocity rate at the inlet and outlet of parallel branch pipes. The results show that the pressure difference between the inlet and outlet of the parallel pipeline system has a certain influence on the flow distribution, and the change of the pipe diameter has a great influence on the flow distribution. The axial momentum recovery coefficient, lateral momentum correction coefficient, axial velocity rate and local resistance coefficient are used for the flow characteristics. It is found that the axial momentum recovery coefficient increases in the manifold tube and decreases gradually in the collector tube, and the lateral momentum recovery coefficient at the inlet of the first nine branch tubes increases gradually. At the entrance of the tenth branch, the lateral momentum recovery coefficient at the outlet of the parallel branch showed a tendency of first increasing and then decreasing, and for the axial velocity rate at the inlet and outlet of the parallel branch, The law of variation is basically the same as that of the coefficient of lateral momentum recovery, but it is different in numerical value. In view of the actual situation, the local resistance coefficient is defined from the point of view of conservation of energy. The numerical results show that the local loss of each section of the manifold pipe increases gradually along the flow direction, and decreases gradually in the collecting tube, and the loss along the parallel branch pipe changes sharply near the branch pipe inlet. When the fluid passes through the eddy current zone, with the full development of the fluid, the variation of its loss along the path tends to a constant value. The results also provide a numerical method for directly solving the fluid flow characteristics of a three-dimensional parallel pipeline system. It provides an effective method for early design of industrial application.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U171

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