Study On Unexpected Pump-stoping Water Hammer Protection In High Lift And Large Flow

With the quickening of urbanization in China and the greatly improvement of people’ living level,water consumption inereased continuously.Superadd the distribution of hydropower resources over this country and the increasing pollution,we build a mass of water conveyance project to meet the need,especially the high-lift and large flow water conveyance project.In these project.the most common and most seriously problem is how to ensure the safety running of the project.Therefore,in the in the practical project using the reasonable and effectivel measure of preventing water hammer is important for the safety running of water conveyance project,it is neeessary to have a further discuss on this problem..A corresponding relation between protection of the water hammer accident and the practical project, the choice of protective measures of different project is diverse.this paper based on the Yellow River pumping station project in center of Shan xi,according to the characteristics of high lift,large flow and large power of water pump set(the largest in china),we have make a mass of calculation,analysis and study.Firstly, the significance and research status at home and abroad of accidental stop pumping water hammer research are stated, the basic principles of water hammer calculation are analysised and boundary conditions under different working conditions are provided. According to the characteristic line method of water hammer calculation, the basic calculation mathematical model of water hammer and the mathematical model of different type pumps in parallel are established in order to laid the theoretical basis of water hammer protection for the later research.Secondly, three types of water hammer protection measures are stated which emphasis the study of air valve, and then carried on deeper discussions. Meanwhile, boundary conditions of the specific protective measures and how to reasonable select and collocate protective measures are provided.Thirdly, the visual program of water hammer calculation is programmed in matlab. And stopping pump water hammer hydraulic transient processes under the conditions of the pump export without any valve, two stages of slow closing butterfly valve and air valve under different protection measures are simulated on the computer.Lastly, run the computer simulations and analyses combinning with central shanxi Yellow River pumping station project. According to the simulation results, the two-stage optimal slowly-closing butterfly valve closing procedure and reasonable air valve installation position are obtained; high head,large flow stops pumping water hammer accident of optimal water hammer protective measures are proposed:two stage slowly-closing butterfly valve is installed at pump outiet, combining with the actual reasonable decorate air valve on the line. It provides a reference for the high head big flow water pipeline water hammer analysis.