水电站压力管道水击计算改进研究

发布时间：2018-05-17 21:39

本文选题：水击现象 + 经典水击理论　；参考：《昆明理工大学》2017年硕士论文

【摘要】：国内外学者开始研究水击是从19世纪开始的,至今已经有了100多年的历史。这种发生在有压管道中的水力现象,具有很大的危害,是水电站及泵站中不可避免的。管道中高低交替的水击压强可能会引起管道的剧烈震动、噪音、变形,严重时甚至会使管道直接爆裂。虽然水击现象已经有了 100多年的研究历史,但其经典理论依然有可改进的地方。想要得到更为符合实际和精准的研究结果,就需要对经典水击理论进行探讨,这样才能为后面的研究内容打下夯实的基础。本论文首先对经典水击理论进行了详细的介绍,包括对水击现象及其分类进行了介绍分析,而后对经典水击理论的基本微分方程组进行了详细的推求,进而在推求过程中提出自己的想法,即经典水击理论并没有考虑管道内流体的流速水头,这可能会对计算结果产生一定的影响。本文针对这一问题,重新推导了运动方程及连续性方程,并使用特征线法对此方程组进行数值计算,在FORTRAN平台上进行编程,并绘制了末端断面水击压强随时间的变化特性曲线。计算结果虽然好于经典水击理论,也与国外类似的试验结果相符合,但并没有改善经典水击理论计算结果衰减性过慢的情况。然后本文选取随流体一起运动的有限控制体建立的微元体,使用动量定理及质量守恒定律严谨推求并创建了完整的一维非恒定流基本微分方程,附加初始条件,进而推导出用于水击计算的运动方程及连续性方程,结合液体弹性方程及管壁弹性方程,组成了新的数学模型。在数值计算方法的选取上,由于特征线法在此数学模型上使用过于繁琐,故本文选取了差分法对其进行计算,建立了差分方程并给出了边界条件和初始条件,在Matlab平台上进行编程计算,最终同样绘制了末端断面水击压强随时间的变化规律曲线图。最后,本文对以上两种计算结果与经典水击理论进行了对比分析,发现建立的第二个数学模型最符合国外类似试验结果,也改善了经典水击理论水击压强衰减过慢的情况,从而证明了本文创立的数学模型的准确性。本文的探求内容对经典水锤理论进行了完善,在学术研究上有理论意义,还为工程实例的计算提供了更为丰富的参考信息。
[Abstract]:Scholars at home and abroad began to study water hammer in the 19 th century, which has a history of more than 100 years. This kind of hydraulic phenomenon occurring in the pressure pipeline has great harm and is inevitable in the hydropower station and pumping station. The alternating high and low water hammer pressure in the pipeline may cause the pipe to vibrate, noise, deform and even burst directly. Although the phenomenon of water hammer has been studied for more than 100 years, its classical theory can still be improved. In order to obtain more practical and accurate research results, it is necessary to discuss the classical water hammer theory, so as to lay a solid foundation for the later research. In this paper, the classical water hammer theory is introduced in detail, including the water hammer phenomenon and its classification, and then the basic differential equations of the classical water hammer theory are deduced in detail. Then the author puts forward his own idea that the flow velocity head of the fluid in the pipe is not considered in the classical water hammer theory, which may have a certain influence on the calculation results. In this paper, the equations of motion and continuity are rederived, and the equations are numerically calculated by the method of characteristic line, and programmed on the FORTRAN platform, and the characteristic curves of the variation of water hammer pressure on the end section with time are plotted. Although the calculated results are better than the classical water hammer theory and are in agreement with similar experimental results abroad, it does not improve the slow attenuation of the calculated results of the classical water hammer theory. Then, the differential equations of one-dimensional unsteady flow are derived by using momentum theorem and the law of conservation of mass, and the initial conditions are attached to the differential equations of one-dimensional unsteady flow, which are established by the finite control body moving with the fluid, and the momentum theorem and the law of conservation of mass are used in this paper. Furthermore, the equations of motion and continuity for water hammer calculation are derived, and a new mathematical model is formed by combining the elastic equations of liquid and the elastic equations of pipe wall. In the selection of numerical calculation method, because the characteristic line method is too complicated to be used in this mathematical model, the difference method is selected to calculate it in this paper, the difference equation is established and the boundary conditions and initial conditions are given. By programming on Matlab platform, the curve of water hammer pressure changing with time at the end section is also plotted. Finally, by comparing the above two results with the classical water hammer theory, it is found that the second mathematical model is the most suitable for similar test results abroad, and it also improves the situation that the water hammer pressure attenuation is too slow in the classical water hammer theory. Thus, the accuracy of the mathematical model established in this paper is proved. The content of this paper improves the classical water hammer theory, has theoretical significance in academic research, and provides more abundant reference information for the calculation of engineering examples.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV732.4

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