| With the rapid development of the industrialization and the urbanization, the demand for water supply is increasing. Meanwhile, the time and space distribution of water resource is uneven in China. More and more Long-distance water supply projects had to be built to solve increasingly sharp contradiction between the supply and demand of water. At present, moving toward large-scale and network development, the long-distance water supply projects are becoming more complex.The sudden changes of the flow velocity is caused by opening or closing the valve and starting or stopping suddenly the pump in the pressure water supply system, which can lead to the rapid spread of pressure wave along the line and the sharp increase or reduce of the pressure within the water pipe. This phenomenon is called water hammer or hydraulic transition process. The water hammer caused by stopping pump due to an accident has an important effect on the safe operation of water supply projects, which can result in the present 1.5-4 times higher than normal. The pressure generated by the cavities collapsing water hammer is greater. Many water supply projects have been severely damaged by pump-stopping water hammer due to an accident. It caused great losses of the people's production and daily life. Therefore, the theoretical analysis, the forecast and control study of hydraulic transition process within the water pipe have great theoretical significance and practical value.Then the appropriate water hammer protection measures must be taken to ensure the safety and stable operation of water supply projects.The main contents of this study are as follows:(1) Analysis of the steady-state operation characteristics on water supply pump station. In different combination operation of pumps and variation water level of the access pool conditions, the operating point of pump and the various hydraulic elements of pump station corresponding to the operating point of pump were confirmed by the computer simulation of steady-state operation characteristics on water supply pump station. Thus the stable work area of pump and the pumping flow, head and efficiency were determined. Making the pumps running in high efficiency zone as far as possible is a good way to realize saving energy and reducing consumption.(2)The mathematical physics model of the pipeline flow was described in detail, including the derivation of motion equation and continuity equation. The method of characteristics used to calculate the water hammer and the pump boundary conditions were discussed. These laid the corresponding theoretical basis for the computer simulation of hydraulic transition process.(3)The Hydraulic transient model was improved. Based on introducing the calculation of friction coefficient on steady flow and analyzing the influence of resistance items to the calculation of water hammer by water hammer equations, the MIAB model was used instead of the traditional processing method of friction. The water hammer characteristic equations were established on the basis of the MIAB model. The optimum calculation method of hydraulic transition process was studied. Applied in the computer simulation of hydraulic transition process in the pressure water supply system, the improvement model of calculating hydraulic transition process has the characteristics of the methods is advanced, high precision and fast convergence. This is the innovation of this study.(4) According to the intake and exhaust principle of air valve and the traditional mathematical model of air valve, the R-K equation which is modified by van der Waals equation was used instead of the ideal gas equation. Thus the improved mathematical model of air valve was established. The new model can meet the engineering calculation requirements, and optimize the calculation of water hammer protection with air valve. Thereby it can provide the theory basis and the technical support for the selection and setting of air valve. This is another innovation of this study.(5) Combined with the engineering practice, Based on Visual Basic 6.0 and SQL Server 2000 database, the computer simulation system of hydraulic transition process on pump station was designed. The features of the computer simulation system are complete functions, reliable performance, friendly interface and easy operation. According to the computer simulation of hydraulic transition process on the example of practical engineering, the reasonable protection measures for water hammer were given. At the same time, the optimization program of butterfly valves and the setting position of air valve were confirmed. Thus the safety and economical operation mode was provided in the water supply system.
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