The Research Of Water Hammer Caused By Pump Failure In Yumenkou Water Supply Project

Hydraulic transient calculation of long-distance water supplying project has become one of the most important subject in the project safe operation. Yumenkou water supply project is a long-distance water supply project. Because its long-distance pipes and complex laying topography, the protecting question of the pipeline has become a key question for the water supply attemperment. The pressure of pipeline system in the state of pump ceases abruptly and abnormally, which is an important factor that affects the safety and credibility of pipeline. This paper mostly calculated and analysed water hammer problem when the pump abnormally ceases abruptly.There are many methods to calculate water hammer such as analytic method,graphic method and the mathematics method of diagnostic line. The analytic method is easy to use and it can reflect the entire process of water hammer, but it has too much workload. Besides it neglects too many factors such as resistance coefficient of pipeline, which do not harm big effect on short pipelines. However it can not be neglected for long pipelines. Sometimes resistance coefficient is centralized at the begining of pipeline when using graphic method, which have big differences in actual situations. Besides it may have cumulative error when using graphic method, and it is difficult to calculate some complex pipeline. The mathematics method of diagnostic line could avoid those shortcomings. It do not only have definite physical conception, but also have great solutional precision. It is quite prompt and precise using computer to solve complicated unsteady problems.Through the pump working point and the operation status of pumping station system of first and second stage pump stations on various conditions of stable operation were analysed and studied, and the pump gearshift adjustment was calculated by hydraulic simulation, we gave the theory basis to make sure the best operation mode when the pump was operating. On the basis of the characteristics of the filling and emptying system of long-distance water supplying project and intake-exhaust valve with multiple point measurement, by comparing the water hammer calculating methods, we adopted the eigenfunction method of numerical simulation calculations of the transient flow in conduit under pressure, made simulated calculations of water hammer caused by power failure on various conditions of water supply system, when taking two-moment delay-shut butterfly valve as the safe measure of pressure pipeline. We got the most pressure of the beginning pipeline exceeded the criterion and threatened operation safety of the pressure pipeline seriously. Therefore, we must take butterfly valve and intake-exhaust valve as joint defense. Combining the method of equal-mete pipeline and adjusting wave-velocity method, automatic subsection method in water hammer calculation is established and has applied in water hammer calculation of intake-exhaust valve in this paper. Not only establishing the calculation-methodological rationality and easy-using, but also putting forward the practical application-conclusion of intake-exhaust valve in water supply project, through the application and calculation-analysis in Yumenkou water supply project establishment of the calculation model of enter-exhaust valve.