多分支并联管道流量分配机理及算法的数值研究

发布时间：2018-03-26 03:08

本文选题：并联管道　切入点：层流　出处：《兰州交通大学》2014年硕士论文

【摘要】：常见流体在多分支并联管道中的流量分配问题具有极其广泛的工程应用背景，其中U型和Z型结构为实际工程应用中常见的两种经典并联管道模型。这两种多分支并联管道形式是石油化工、火电、锅炉、太阳能、核电、制冷等领域常用的重要流量分配装置。流体工质在此类并联管道中的流动状况（如流速、流量分配等）直接关系到设备的安全可靠性和经济性。从而，如何设计合理的管道系统来实现流量的均匀分配非常重要。为此，本文采用数值分析的方法对不同进出口压差及不同管道几何参数条件下并联管道系统内流体的流动特性进行了研究。论文研究内容有：建立并联管道系统的流动模型；对所研究的并联管道区域进行离散；发展同位网格下已知压力边界条件的SIMPLE算法；计算在不同并联管道进出口压力差，不同集管管径条件下，管道系统的流动特性；进而对流动特性用常用的参数进行了表示，如轴向动量恢复系数，侧向动量修正系数，压降以及并联支管进出口处的轴向速度率。结果表明，并联管道系统进出口压力差的变化对流量分配产生了一定影响，集管管径的变化给流量分配产生了较大的影响；在一定的条件下，若想获得较好的流量分配，可以尽可能增大集管管径。对流动特性采用轴向动量恢复系数、侧向动量修正系数、轴向速度率、局部阻力系数、沿程阻力系数等进行了表征后发现：轴向动量恢复系数在分流集管中是波动增加的，在汇集集管中是逐渐减小的；前九个支管进口处的侧向动量恢复系数在是逐渐增大的，第十个支管进口处出现了下降的情况，各并联支管出口处的侧向动量恢复系数呈现出先增大后减小的趋势；对于并联支管进出口处的轴向速度率，其变化规律与侧向动量恢复系数的变化规律基本上相同，只是在数值大小是有差别；对于局部阻力系数的研究，鉴于实际情况，从能量守恒的角度对其进行了定义，数值结果表明分流集管中每段管道部分的局部损失沿流动方向是逐渐增加的，，汇集集管中是逐渐减小的；各并联支管中的沿程损失在靠近支管进口处变化比较剧烈，待流体通过涡流区后，随着流体的充分发展，其沿程损失变化趋一常值。研究结果还提供了一种可直接求解三维并联管道系统流体流动特性的数值方法，为工业应用的前期设计提供有效的方法。
[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.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U171

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