Waves Propagating in Water-Filled Plastic Pipes Due to Leak Noise Excitation: A Numerical and Experimental Investigation

Water loss has been one of the main concerns of water distribution companies in many countries for many years. Among the techniques used to detect and locate leaks in buried water pipes, leak-noise correlators are routinely employed. This method uses the measurements of pipe vibration due to leak noise that propagates along the pipe. Studies suggest that the predominantly fluid-borne wave carries most of the leak energy. In this paper, however, it is shown experimentally that two wave-types can propagate in an in-air plastic pipe when excited by a leak source. One wave-type is related to the predominantly fluid-borne wave, characterized by a low-frequency content. The other wave-type is predominant in the pipe wall. This wave is not well coupled to the fluid and has high-frequency content. A bespoke test rig is used to perform measurements and to collect pipe vibration data related to leak-noise under controlled conditions. The experimental data is used to show the presence of these two wave-types. Numerical results using the finite element method are also presented and validated against experimental data. Further, a discussion of the physics behind the phenomena is presented using analytical and numerical models.