Study Of Hydrodynamics System Of The Free-surface-pressure Flow In Long Distance Water Diversion Project And Its Application

The shortage and uneven distribution of our country’s water resources has brought great pressure to the development of the economy and society. For the purpose of finding ways to solve the difficulties of water-using, a large number of long distance water diversion projects have been built in our country, which makes the dispatch become the most important part of water diversion. It is too hard to simulate operations experimentally because of the wide water area and huge numbers of control buildings of the long distance water diversion project. But we can’t ignore that we are not able to bear the results of engineering accident without calculation and simulation. Numerical simulation methods have been largely used by many researchers due to their economic and convenient characters. And it has a great significance to find a more practical and secure numerical simulation method to the whole water diversion project.By studying the previous relevant theoretical research proposed by other researchers, this article established a one-dimensional unsteady free-surface-pressure flow hydrodynamic system which is suitable for long-distance water diversion project with complex inner boundary. In order to simulate the characters of the flow accurately and analysis the stability and safety the flow brought to the project, Saint Venant equations and Preissmann slit method are used to calculate pressure flow, free-surface flow and the transition flow between these two states, to discrete the model equations, the stagger mesh and implicit method were also used. From these methods, we can make sure that the discrete scheme had great neoconservatives and stability, and it can also get rid of the restriction of the number of crown, improve the computing efficiency and save a lot of time in calculation. Besides, reservoirs, pump stations, diversions, culverts, sluices and other hydraulic structures were put into the system.This system has been used to simulate looping network and Wiggert experiments, which lead to results agree with the experiment results, being proved to simulate one-dimensional free-surface-pressure flow well. What’s more, it has been used to simulate the hydraulic characteristics under normal condition of Beijing section of the first phase in South-to-North Water Diversion Project, problems brought by free-surface-pressure flow could be solved more efficiently. And by comparing the simulated values and measured values at key points, it shows higher accuracy. At last, we have simulated the emergency condition and second phase conditions in South-to-North Water Diversion Project, and have analyzed the flow distribution and water level changes. Results show that the system can provide reference for the optimal design of long distance water diversion project and dispatch decision of related departments. It has been indicated that this method could be used in large-scale water diversion projects with free-surface-pressure flow.