Water hammer suppression for long distance water supply systems by combining the air vessel and valve

Abstract

In long distance water supply projects, the air vessel is an effective and reliable protection measure to control water hammer. Although it can effectively eliminate water hammer during the process of hydraulic transient, the volume of the traditional air vessel is large due to the long distance pipeline, resulting in high investment. In this paper, based on the analysis of the transient in long distance water supply pipelines, a protection method, combining the air vessel with the downstream valve, is proposed to reduce the volume of the air vessel, keeping the system pressure within the limit. Furthermore, an innovative arrangement of the air vessel is presented to overcome the risk of the combined protection method. Besides the upstream air vessel, a downstream air vessel is additionally installed to mitigate positive water hammer due to rapid closure of the downstream valve. To verify the effect of the new method, the numerical model was established according to the parameters of a practical water supply project, and hydraulic transient due to pump trip was simulated. Compared with the traditional method, the combined protection method provides effective water hammer protection and greatly reduces the volume of the air vessel.