城市给水管网水力特性分析研究

发布时间：2018-03-13 12:05

本文选题：给水管网　切入点：水力特性　出处：《沈阳建筑大学》2013年硕士论文　论文类型：学位论文

【摘要】：城市给水工程主要是由取水工程、水处理工程和管网系统三部分组成。其中,城市管网系统的主要任务是将满足标准的饮用水输送到千家万户,以满足城市居民生活、生产的用水要求。城市管网作为重要的市政设施,其投资费用可占整个给水工程总费用的50%-80%,并且,每年还要为市政管网的扩建、改造和维修投入大笔的资金。因此,了解城市管网的运行现状和水力特性,及时获取其运行状态数据,对城市管网进行科学管理是十分必要的。多年来许多国内外专家致力于给水管网水力特性的计算和方法的研究及其运用。图论理论的逐步完善和发展,为研究者构造给水管网的节点方程和环方程提供了数学依据,伴随着计算机技术的不断完善,为矩阵的解析提供了便捷的算法。节点方程和环方程在计算机技术的配合下,提供了简洁明了的矩阵描述方式,使人们对管网系统、矩阵本身的解析及应用的了解更直观、更简明。并且,求解这些方程的各种方法在计算机上得以完成和实现。管路特性曲线是描述管路中流量Q和总压力H的关系曲线,它给出了管路在某一流量下的总水压。在给水管网设计、泵站设计以及泵站的选择时,都会通过将管路特性曲线和水泵特性曲线联立,确定水泵工况点来完成选泵的工作,于此同时,在泵站的扩建与维修时,也会用到管路特性曲线。通过管网水力计算,可以了解每一条管段的水力情况,但却不能像管路特性曲线反映管网的整体水力情况,理论上,管网特性曲线的形式应该有所变化,可是大多数的研究者都忽视了这一变化,在泵站设计时依旧采用传统的管路特性曲线的形式,这导致了确定的工况点与真实值之间存在偏差。目前关于城市管网特性曲线的研究不多,而且都仅仅是从定性的角度分析管网特性曲线,都有很多局限性。于此同时,管网不同,特性曲线也有所差异,因此,管网特性曲线应根据管网的具体情况加以分析。最小二乘法是一种数学优化技术。它通过最小化误差的平方和寻找数据的最佳函数匹配。利用最小二乘法可以简便地求得未知的数据,并使得这些求得的数据与实际数据之间误差的平方和为最小,最终获得最佳函数。本文在管路特性曲线的基础上,利用最小二乘法,通过最小二乘估计的分析方法,拟合城市给水管网用水量和最不利管线之间的总水压曲线关系,分别拟合一次直线,二次曲线和三次曲线,依次对拟合结果评价,判断曲线是否具有统计学意义,并通过拟合优度选择最佳的拟合曲线。
[Abstract]:Urban water supply projects are mainly composed of three parts: water intake projects, water treatment projects and pipe network systems. Among them, the main task of the urban pipe network system is to transport drinking water that meets the standards to thousands of households in order to meet the needs of urban residents. Water requirements for production. As an important municipal facility, the investment cost of the urban pipe network can account for 50 to 80 percent of the total cost of the water supply project, and a large sum of money will be invested every year for the expansion, renovation and maintenance of the municipal pipe network. It is very necessary to understand the operation status and hydraulic characteristics of urban pipe network and to obtain the data of its running state in time, so as to carry out scientific management of urban pipe network. Over the years, many experts at home and abroad have devoted themselves to the study and application of the hydraulic characteristics of water distribution networks. The gradual improvement and development of graph theory provide a mathematical basis for researchers to construct node equations and ring equations of water supply networks. With the continuous improvement of computer technology, it provides a convenient algorithm for matrix analysis. With the cooperation of computer technology, node equation and ring equation provide a simple and clear matrix description method, which makes people have a good understanding of the pipe network system. The analysis and application of the matrix itself are more intuitive and concise, and the various methods of solving these equations have been completed and implemented on the computer. The characteristic curve of pipeline is a curve describing the relationship between the flow rate Q and the total pressure H in the pipeline. It gives the total water pressure of the pipeline under a certain flow rate. In the design of the water supply network, the design of the pump station and the selection of the pump station, Both the characteristic curve of pipeline and the characteristic curve of pump will be combined to determine the working point of pump to complete the work of selecting pump. At the same time, the characteristic curve of pipeline will also be used in the expansion and maintenance of pumping station. Through the hydraulic calculation of pipe network, we can understand the hydraulic situation of each section of pipe, but it can not reflect the whole hydraulic situation of pipe network as the characteristic curve of pipe line. In theory, the form of characteristic curve of pipe network should be changed. But most researchers ignore this change, and the pump station is still designed in the form of a traditional pipeline characteristic curve. This leads to the deviation between the fixed working point and the real value. There are few researches on the characteristic curve of urban pipe network, and all of them are just qualitative analysis of the characteristic curve of the pipe network, which has many limitations. At the same time, The characteristic curve of pipe network is different, so the characteristic curve of pipe network should be analyzed according to the concrete situation of pipe network. The least square method is a kind of mathematical optimization technique. It can find the best function match of the data by minimizing the sum of square of error. Using the least square method, the unknown data can be easily obtained. The squared sum of the errors between the obtained data and the actual data is minimized, and the optimal function is obtained. On the basis of the characteristic curve of the pipeline, using the least square method and the analysis method of the least square estimation, the relationship between the total water pressure curve of the urban water supply network and the most unfavorable pipeline is fitted, and a straight line is fitted respectively. The conic curve and the cubic curve evaluate the fitting result in turn, judge whether the curve has statistical significance, and select the best fitting curve through the goodness of fit.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU991.33

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