【作者】 杨宝奎；

【导师】 朱满林； 张晓宏；

【作者基本信息】 西安理工大学 ， 水文学及水资源， 2007， 硕士

【摘要】 由于我国工业的迅速发展、人民生活水平的提高和城镇化进程的加快,城市的需水量增加很快,就近取水已远远不能满足人民生活和生产的需要,加之我国水资源时空分布又极不均匀,由此带来的水资源供需矛盾日益加剧,很大程度上制约了社会经济的发展和人民生活水平的提高。为满足用水需求,确保供水,以南水北调工程为显著标志的跨流域调水、远距离输水工程越来越多,其管线往往受多种因素的影响,将呈现出起伏变化复杂的显著特点。当系统发生水锤事故时,在管道的局部位置,会因水锤降压的影响而出现吸气、气体释放、液体汽化乃至水柱分离现象;当水锤升压时,又可能会造成升压很高的断流弥合水锤,这些现象将使整个输水系统无法安全运行。因此,对泵输水系统水锤进行正确的分析,对其过渡过程进行准确的预测,从而合理地选择防护措施,是优化工程设计、确保工程安全运行的关键,对于保障生活生产用水及社会经济的发展,具有非常重要的意义。本文的主要内容如下:(1)阐述论文的研究目的意义,输水系统水锤现象的发生机理、分类、研究理论及分析计算方法,简述水锤研究的现状。(2)总结并给出目前国内外常用的主要水锤波速计算方法。论述水锤的基本微分方程及特征线计算方法,运用特征线法建立简单管路系统与复杂管路系统中常见的边界条件,包括(上、下游)水库、(正常运行工况)水泵、(管道中、末端)阀门、串联管系与分叉管系。(3)简述水锤计算中常用的压力管道分段方法,对调整波速法进行研究,提出了改进的调整波速法。(4)建立水泵机组事故停机边界条件,包括单泵、串联泵、并联泵、带旁通管泵组,并进行数值计算。(5)简述水力瞬变过程中空穴的成因及其流态特征,建立计算气液两相瞬变流的主要数学模型。(6)论述长距离泵输水系统常用的水锤防护措施及其装置构成、防护机理、设计要点、特性等。建立相应的边界条件,包括简单调压塔、单向调压塔、空气阀、两阶段可控蝶阀。阐述管道进排气设计及空气阀存在的问题。(7)通过编制的计算机程序,对陕西榆林某电厂供水工程进行水锤分析计算,并提出合理的防护措施。更多还原

【Abstract】 With the development of industry, improvement of living standard and further development of towns and cities, water demand of cities is increasing rapidly. It is hardly to satisfy the water demand of living and industrial manufacture by only using water resources nearby these cities. In addition, the water resource distribution is quite uneven both in time and space over China, the conflict of water supply and demand is further worse, and the development of the economy and living standard are restricted. In order to meet the water demands ensure the normal water services, more and more long distance water transmission projects are founded, in which Water Diversion Project from South to North is the prominent milestone. Many factors affect the pipeline arrangement of long distance water transmission work, which make the elevation change of the pipeline vary greatly. When water hammer takes place, pressure will decrease in some parts of the pipeline, inspiration, gas release, liquid vaporization and water column separation may happen, while when pressure is increasing in turn, water interception collision may appear and the pressure can be extremely high. These will make the whole water supply system totally unsafe. So correct analysis water hammer of pumping water supply system, exact prediction its transient processes and rational selection the protection plan are very important to the engineering design optimizing and project safe operation guarantee, and have significant meaning and practical value to the water supply and economic development.The dissertation consists of the following contents:(1) The paper presents the purpose and significance of the research, tells the mechanism, classification, theory and analysis and computing methods of water hammer in water transmission system, and summarizes the current situation of water hammer.(2) The paper summarizes and presents the mainly used computing methods of water hammer wave velocity, gives the basic differential equations of water hammer and method of characteristics, details common boundary condition of method of characteristics in simple andcomplex pipeline system, including upriver and downriver reservoir, normal operating pumps, valves in pipeline and at the end of pipeline, pipe in series and branch piping.(3) Some conventional methods of sectioning of preesure pipeline system are introduced, and wave velocity method is studied and improved.(4) The boundary conditions of pump units closed-down in accident is established, including single pump, pump in series, pump in parallel, pumping set with by-pass pipe, and the numerical calculation is carried out.(5) The paper discussed the cause of formation and characteristics of gas cavity in hydraulic transient, and establishes primary calculate models of two-phase hydraulic transient of gas-liquid.(6)The paper expounds the constitutes of the equipment, protection mechanism, design point and characteristics of the common water hammer prevention measures in long distance pumping water supply system. Moreover, the corresponding boundary conditions of water hammer prevention measures, including simple surge tank, one-way surge tank, air valve, and two-phase butterfly valve control, are founded. Meanwhile, the design of air input and air exhaust of pipeline and the existing problems of air valve are simply discussed.(7) Analysis and calculation of water hammer in water supply project of an electricity plant at Yulin in Shaanxi Province are carried out, and properly water hammer prevention measures are given out.更多还原