Effects of Surge Tank Geometry on the Water Hammer Phenomenon: Numerical Investigation

Abstract A surge tank, as one of the most common control facilities, is applied to control head pressure level in long pressurized pipelines during the water hammer occurrence. The cost-effective operation of surge tank is highly affected by its characteristics (i.e., surge tank diameter and inlet diameter of surge tank) and can effectively reduce the repercussion of water hammer. This investigation utilized the method of characteristics (MOC) in order to simulate the behavior of transient flow at surge tank upstream and head pressure fluctuations regime for hydraulic system of a hydropower dam. The various types of boundary conditions (i.e., sure tank, reservoir, branch connection of three pipes, series pipes, and downstream valve) were applied to numerically investigate the simultaneous effects of the surge tank properties. In this way, all the simulations of water hammer equations were conducted for nine various combinations of surge tank diameter (D) and inlet diameter of surge tank (d). Results of this study indicated that, for the surge tank design with D=6m and d=3.4m, head pressure fluctuations reached minimum level in the large section of pipeline here is surge tank upstream. Additionally, occurrence of water hammer phenomenon was probable at the initial section of pipeline.