The Effect Of Surge Tanks In The Process Of The Protection Towards Water Hammer Fluctuation In Long-distance Pipelines

With the accelerated process of urbanization, urban water demand is alsoincreasing. Subject to geographical constraints, many regions require trans-regionalwater transportation. Meanwhile, the scale is becoming larger and larger and thedifficulty is increasing as well. The hydraulic transients caused by the water hammercan cause pipe explosion accidents and a great loss of property. Thus, how to effectivelyreduce the water hammer pressure is the key to the security for the program designers.In this paper, based on method of characteristics, a hydraulic transient model wasbuilt in order to explore the pressure reduction effect after a surge tank was set in thepipeline. At the beginning, a study of wave reflection and reduction of water hammerpressure of the simple cylindrical surge tank was made. By changing the location wherethe surge tank is set, we can search for an optimal place that the reduction effect can bethe best. Subsequently, various factors that affect water hammer pressure and waterhammer flow changes can be explored, while remaining the other parameters constantand respectively changing the length of the pipeline, diameter size of the pipe, the waterlevel of reservoir and surge tank parameters such as the cross-sectional area. In addition,two more complex models of throttled surge tank and dual-chamber surge tank weremade to study their features and scope of application in the hydraulic transients.Because the pipeline is always installed with some other hydraulic devices, andthese hydraulic components are coupled and nested together, we obtain a model with thecombination of surge tank and mid-valve by replace part of the boundary conditions.Based on the theory of reduction effect of the mid-valve, a surge tank was setrespectively on the two sides of the mid-valve to search for the best effect. The pressurethat the tank is set at the left side of mid-valve is the minimum, namely57.9m, less thanthat of the two valve case (72.97m) and that of the surge tank case (64.74m). Finally, byuse of a pipe network hydraulic analysis engineering software AFT Impulse, theexamples above were being simulated thus to compare with those previous model, andthe suit result was analyzed as well. In fact, basing on the method of characteristics andprograming the boundary conditions can have wide coverage areas in terms of thecomputational details. However, the programming process takes a rather long time,while AFT Impulse with simple operation and a solution of high efficiency can get amore convenient advantage.