水击基本理论研究

发布时间：2018-04-02 13:26

本文选题：水击现象　切入点：非恒定流　出处：《郑州大学》2014年硕士论文

【摘要】：本论文首先对经典水击基本微分方程及计算方法进行了介绍分析，指出了其基本理论和数值算法中可能存在的一些问题，如经典水击连续性方程不能恒满足恒定流条件、水击计算结果的衰减性不符合实际情况、倾斜项存在的不合理性、应用动量定理时所选研究对象在时段初、末不一致、 ds/dt=v和ds/dt=c的概念混淆等问题。接着，本论文对水击基本方程进行了进一步推导和分析，特别是针对水击波的传播特性，，采用严谨的水击现象传播图示，严格的推导了水击波的运动方程，其结果与经典水击运动方程一致，验证了水击运动方程的正确性。同时，分析了水击连续性方程存在的问题及原因。对于水击计算的特征线法，考虑波速的影响，采用库朗格式计算，对水击计算结果的衰减性有所改善，但仍与实际情况相差甚远。水流流速的忽略并不是造成水击计算结果不衰减的根本因素。通过对恒定流和非恒定流情况下管壁剪切力模型的分析和计算，说明剪切力模型形式对水击问题的衰减性有一定关系。然后，本论文通过将一维非恒定流基本微分方程组联合液体弹性方程与管壁弹性方程后组成的完型方程组，进行了水击问题的数值计算，得出了较为满意的关于水击压强、水击波速、管道断面面积以及液体密度的变化规律的结果，能够较好的符合实际情况，在理论研究及工程应用中均具有重要意义。最后，本论文通过对完型方程组的进一步计算分析，对水击的类型分类以及阀门或导叶开度等因素对水击压强的影响进行了验证和定量分析，对定性分析水击现象提供了技术手段和技术支持。
[Abstract]:In this paper, the basic differential equation and calculation method of classical water hammer are introduced and analyzed, and some possible problems in its basic theory and numerical algorithm are pointed out. For example, the classical continuity equation of water hammer can not satisfy the constant flow condition.The attenuation of the results of water hammer calculation does not accord with the actual situation, the irrationality of the slope term, the inconsistency of the objects chosen in the application of momentum theorem at the beginning and the end of the period, the confusion of the concepts of ds/dt=v and ds/dt=c, and so on.Then, the basic equation of water hammer is further deduced and analyzed, especially according to the propagation characteristic of water hammer wave, the motion equation of water hammer wave is deduced strictly by using strict diagram of water hammer phenomenon propagation.The results are in agreement with the classical equation of motion of water hammer, and verify the correctness of the equation of motion of water hammer.At the same time, the problems and causes of water hammer continuity equation are analyzed.Considering the influence of wave velocity, the attenuation of the result of water hammer calculation is improved by considering the influence of wave velocity, but it is still far from the actual situation.The neglect of the flow velocity is not the fundamental factor which causes the water hammer calculation results to decay.Through the analysis and calculation of the shear force model of the pipe wall under the condition of constant flow and unsteady flow, it is shown that the form of shear force model has a certain relationship with the attenuation of water hammer problem.Then, by combining the basic differential equations of one-dimensional unsteady flow with the liquid elastic equation and the tube wall elastic equation, the numerical calculation of the water hammer problem is carried out, and the satisfactory water hammer pressure is obtained.The results of water hammer wave velocity, pipeline cross section area and liquid density can accord with the actual situation, and are of great significance in theoretical research and engineering application.Finally, through the further calculation and analysis of the Gestalt equations, the classification of water hammer types and the effects of valve or guide vane opening on the water hammer pressure are verified and quantitatively analyzed.It provides technical means and technical support for qualitative analysis of water hammer phenomenon.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV134

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