The Computer Numerical Simulation Of Pressure Pipelines Safety Protection In High-lift Pumping Station

In water supply system works, flow rate suddenly changing in pressure piping that create pressure of stream current steep rise or sudden drop, which is also called water hammer or hydraulic transient. Water hammer shall affect largely the normal operation of pumping station, water hammer pressure of general cut-off water hammer is higher 1.5 to 4 times than normal pressure, and the hammer of water column separation can create greater water hammer pressure. Many pumping station had been destroyed badly by water hammer and this cause great loss to the normal production and life for people. Therefore, hydraulic transient calculation of long distance and high lift pump of water supply works has become one of important project. Only when hydraulic transient of pumping station is precede precision & rational numerical calculation, at the same time adopt requirement safety measure of water hammer, which ensure safe operation of pumping station.This article systematic introduces method of characteristic curves of hydraulic transient of pumping station firstly and thenresearches stable operation of pumping station, on the base of it, studying transient characteristic of pump system. Through simulating terminal condition of water pump accident, and establishing mathematical model of water hammer calculation that is under different protective measures of water hammer, which based on the method of characteristic curves. At the same time, applying the proper numerical calculation method, compiling computer simulation program, and carrying through studying combine with the practice embody project. The key research contents as following:1. Based on generalizing predecessor research achievement, systemic formulation the basic principle of water hammer and method of characteristic curves, analyzing operating principle of different water hammer protection measure (such as butterfly valve > waterhammer arrester with the lower open type^ air inlet and vent valve, etc.) , establishing the boundary condition and solving mathematical-hydraulic model.2. Combine boundary condition equation of different model water pump parallel operating and two-stage closedown pilot butterfly valve, which establish suitable hydraulic model for calculation. Through no.9 pumping station's application and calculation at Guhai expansion irrigated area in Ningxia province, analogy calculation on scheme of big pump matching small pumpand optimization protection result of two-stage closedown pilot butterfly valve's close procedure, supply maintenance logistics to water filling of the first time and safe operation for the future.3. According to the characteristic pipeline pressure distribution in long distance water supply works and partial salient point installment air inlet and vent valve, combination equivalent pipeline method and adjustment wave speed method, which establish mathematic model of air inlet and vent valve. Through calculation analysis in Yellow River industrial water supply project in Yumenkou of Shanxi province, which put the conclusion, that air inlet and vent valve is very important to safety protection in water supply works.4. Combination water hammer arrester itself characteristic, which establish hydraulic-calculation model of water hammer arrester. Through application and calculation analysis of the water hammer arrester in No.2 Niangziguan pumping station project of Shanxi province, provide technical basis for safe operation of the pumping station system.5. The hydraulic transient mumerical simulation of three project items mentioned above is based on steady-state operation study of water supply works, thus make the result of water hammer calculation more press closer to practice, it is of innovation;6. Adopting Visual Basic to exploit good interface, highinteractive, credibility performance and simple operating computer numeric simulated system that is applied in hydraulic transient of water supply works.At the end of the paper, carrying through analysis to the calculation result mentioned above, studying on calculation error's reason, at the same time, putting the further research problem that is existence in the calculation of water supply woks hydraulic transient.