Complex Pipeline Network System Transient Flow Simulation

With the development of national economy, the consumption of gas is rising increasingly; gas pipe network system becomes more and more enormous and complex. However,transient flow in pipe network system will be caused when large users start to run or to close. The hazard made by transient flow can result in intensive breakage of pipeline. In order to guarantee the reliable and safe function of the gas pipe network, it's required to research on gas pipe network more deeply and widely, and it needs to carry out dynamic calculation and simulation on gas pipe network during the design and function of pipe network. Its practical application has a remarkable instructive meaning on improving the reliability and efficiency of the function of gas pipe network system, which has an immense economic value.By now, the research on transient flow has not been studied deeply in our country. The research on transient flow mainly focuses on long pipelines, such as hydraulic pipeline and natural gas pipeline. The object studied is always ring or tree-like structure pipe network singly, without pipe network units(such as tee joints, valves), the complex one which includes both ring and tree-like structure pipe network with pipe network units is studied rarely, the relevant pipe network system simulation software hardly can be found.In view of the status of research, this thesis studies the research on transient flow, aiming at the complex gas pipe network system which includes both ring and tree-like structure pipe network with pipe network units. The chief achievements are listed below:First, based on the practical characteristics of gas pipe network, the solution of the physical and non-physical parameter of gas is confirmed, and the method that makes pipe network simple is also confirmed. The topological structure of pipe network is established on the basis of graph theory.Then, the mathematical model which can accurately describe the transient flow in gas pipe network is established on the basis of Continuity Equation, Momentum Equation, Energy Equation and the real-gas Equation of State, deduced from fluid mechanics principle, the solution of the mathematical model is confirmed according to comparing several methods, and we solve the mathematical model. Next, the solution of the initial conditions for the calculation and simulation of the transient flow in pipe network is confirmed; the mathematical models of the common boundaries and its solution are confirmed, according to the topological structure of pipe network established above.Finally, a software for the transient flow simulation in gas pipe network is developed using Visual Basic,Access and Excel 2003 as programming tools, according to the mathematical model and its solution process. The simulation software is validated using the data from practical project, and the results support the credibility and rationality of the data calculated by the simulation software. The analysis of simulation results for other cases is done. At last, the prospect of its application is discussed according to the output of the software.