Effects of connecting patterns of branch pipes on superposed water hammer pressure in trunk pipe for the PVC pipeline system

To reasonably design irrigational pipe system and develop the theories of pipe system plan for the pipeline network irrigation district, the effects of inlets of branch pipes with differential spacing interval and diversion angel on the superimposed water hammer in main pipe were studied by experiments and simulations based on the PVC-U dendritic pipe network system. Diameter of PVC-U dendritic pipe was designed as 200mm, the inlets spacing interval of branch pipes as 0, 6.2, 12.4, and 18.6m respectively, and diversion angel as 90°,60°, and 45°respectively. A centrifugal pump with designed head of 28m and designed capacity of 374m3/h was employed to supply pressure fluid to the pipeline system. The results indicated that the corresponding superimposed pressure value in the main pipe increased from 23.5 m to 30.1 m with inlets spacing interval reducing from 18.6 m to 0 m, and the superimposed pressure of water hammer in main pipe increased from 30.1m to 34.9 m with the diversion angel decreasing from 90° to 45°. The superimposed water hammer in main pipe was exponentially lower with increasing spacing interval and the diversion angel of tributary pipes inlets. In dendritic pipe network system, a spacing interval of diversion inlets should be designed in the range of 0 to a half of field width or more, and diversion angel as 90 degree. These results are helpful to the design and operation of the dendritic pipe network system for water delivering and distributing.