Laboratory implementation of the noise correlation methodology for leak location in water distribution systems

Nowadays, reducing the loss of water resources is of primary concern in many countries worldwide. Different methodologies exist for the identification and localisation of leaks in water distribution networks, which can be applied simultaneously at a different scale, to improve success rate. Acoustic correlation has been employed for many years to localise such leakages, based on the post-processing of vibroacoustic signals acquired by two sensors placed on both sides of the pipe where the leakage is supposed to be located. The practical application of this methodology still presents some significant issues. The implementation of the noise correlation methodology was investigated through an experimental test rig by simulating leakages in different conditions of pressure and flow and investigating the effects of background noise. Hydrophonic measurements and recordings were performed, identifying the frequency range affected by the leak noise, and the signal to assess the accuracy of the noise correlation method. A pre-filtering of the signals to reduce the effect of background noise masking was also investigated. The accuracy of acoustic correlation in localising the leakage was assessed by computing the propagation velocity, which depends on the vibroacoustic fluid-structure interaction, through approximated analytical equations