液体管道水击计算方法研究及程序设计

发布时间：2018-09-12 06:49

【摘要】：水击现象是管道安全运行需要避免的情况之一,但由于某些客观因素水击现象的发生不可以避免,所以在管道设计和生产运营时需要在容易受到水击影响到的地方考虑这一因素。目前对于水击压力的计算多是采用国外的管道仿真软件,这些软件的主要用途是用于模拟管道正常运行工况,但是对于水击这一压力波动大、波动快的非正常工况,这些管道仿真软件的计算精度不高。所以在需要考虑水击影响因素时,一个精确的水击计算工具就显示出很高的价值。本论文的研究是通过对目前主要水击计算方法的调研展开的。通过前期调研了解主要计算方法,比较它们的优缺点,重点选取了特征线法和显式差分法做比较,并引入自适应网格,进一步提高计算精度。针对论文研究的液体管道模型,选取了停泵水击和关阀水击两种水击模型作为水击研究的计算模型。并使用Matlab工具来验证特征线法和显式差分法,比较两种计算方法的计算结果,最后选取显式差分法作为水击计算程序的计算方法。同时本文还提出,以密度为变量,使变量的个数达到3个。该方法的原因在于,密度对水击波速的影响很大,而且管内流体的密度是不均匀且变化的。运用visual studio C#编程工具,完成了水击模拟程序的编写。最后通过对具体实例进行水击模拟分析。模拟管道在泵机组突然断电和控制阀失灵关闭情况下发生的水击,得到模拟结果如下： (1)在泵机组断电的情况下,水击压力短时间内升高很快,此后变化较为平缓,断电停泵的同时,由于泵站站后压力高于站前压力,将使泵站发生断流情况。最后当泵站的进站压力高于了出站压力后,管内流体越站流过泵站； (2)在控制阀失灵关闭的情况下,水击压力在水击波返回至阀门处时,阀门端压力处于最大值,此后水击压力逐渐减小,可以得到波速有减慢的现象。在不同的关阀时长的情况下分别模拟的结果可以看出,关阀时长越长,水击造成的最大压力越小,出现时间越晚。本文通过对水击计算的研究,得到了较为精准的水击计算方法,并通过使用自适应网格,进一步提高计算精度。同时编写水击模拟程序,所得到的水击模拟程序具有一定的水击模拟能力,能解决一定的水击分析问题,具有一定的实用性。
[Abstract]:The phenomenon of water hammer is one of the situations that need to be avoided in the safe operation of pipeline, but the occurrence of water hammer can not be avoided because of some objective factors. Therefore, this factor should be taken into account in the design and operation of pipelines where they are vulnerable to water hammer. At present, most of the calculation of water hammer pressure is based on the overseas pipeline simulation software. The main purpose of these software is to simulate the normal operation condition of the pipeline. But for the water hammer, the pressure fluctuates greatly and fluctuates rapidly under the abnormal working condition. The calculation accuracy of these pipeline simulation software is not high. Therefore, an accurate tool for calculating water hammer shows high value when considering the influencing factors of water hammer. The research of this paper is based on the investigation of the main methods of water hammer calculation. In this paper, the main calculation methods are investigated, their advantages and disadvantages are compared, the feature line method and explicit difference method are selected to compare them, and adaptive meshes are introduced to further improve the calculation accuracy. According to the model of liquid pipeline studied in this paper, two kinds of water hammer models, stop pump water hammer and shut off valve water hammer, are selected as the calculation models of water hammer research. The Matlab tool is used to verify the characteristic line method and explicit difference method, and the results of the two methods are compared. Finally, the explicit difference method is selected as the calculation method of the water hammer calculation program. At the same time, it is suggested that the number of variables can reach 3 by taking density as variable. The reason of this method is that the density has a great influence on the velocity of water hammer wave and the density of fluid in the pipe is inhomogeneous and varied. Using visual studio C # programming tool, completed the water hammer simulation program. Finally, the water hammer simulation analysis of concrete examples is carried out. The simulation results are as follows: (1) the water hammer pressure increases rapidly in a short period of time when the pump unit is out of power and the water hammer pressure changes more slowly after the water hammer pipe is suddenly out of power and the control valve fails to close, and the simulation results are as follows: (1) when the pump unit is out of power, the water hammer pressure rises rapidly in a short period of time. At the same time, because the pressure behind the pumping station is higher than the pressure before the station, the pump station will be cut off. Finally, when the inlet pressure of the pump station is higher than that of the exit station, the fluid in the pipe passes through the pump station; (2) when the control valve fails to close, the water hammer pressure is at the maximum when the water hammer wave returns to the valve. After that, the water hammer pressure decreases gradually, and the wave velocity slows down. The simulation results show that the longer the valve is, the smaller the maximum pressure caused by water hammer is and the later it appears. In this paper, a more accurate calculation method of water hammer is obtained by studying the calculation of water hammer, and the accuracy of calculation is further improved by using adaptive grid. At the same time, the simulation program of water hammer has certain ability of water hammer simulation, can solve the problem of water hammer analysis, and has certain practicability.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

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