Acoustic noise characterization for leak detection in water mains
Acoustic emission (AE) method is becoming popular for leak detection in municipal water mains where leaks are identified and the locations are determined through interpretation of measured acoustic signals without any excavation or disruption of services. For the interpretation of signals, several p...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
2017
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| Online Access: | https://research.library.mun.ca/12610/ https://research.library.mun.ca/12610/1/thesis.pdf |
| Summary: | Acoustic emission (AE) method is becoming popular for leak detection in municipal water mains where leaks are identified and the locations are determined through interpretation of measured acoustic signals without any excavation or disruption of services. For the interpretation of signals, several parameters such as frequency band of signals, coherence between signals, and cross-correlation between signals are employed. However, published literature lack data on applicability of the AE method under various field conditions. This research presents field investigation of leak detection using AE method, identification of leak noise source, leak noise attenuation characteristics and finite element (FE) simulation of acoustic wave propagation through fluid filled pipe. The field application of the AE method was performed through measuring acoustic noise at two points bracketing the leak along the pipe length in the City of Mount Pearl in Newfoundland and Labrador, Canada. For a better understanding of the source of leak noise, a preliminary laboratory investigation was conducted under a controlled environment. At low flow rates, it was found that water (escaping from the leak) hits surrounding obstacles and generates the leak noise. To explore the characteristics of leak noise, a new laboratory facility was developed and the attenuation characteristics of the leak noise was investigated. Leak noise attenuation was found to depend on the flow rate of the water. Finally, finite element (FE) method was used for modelling of acoustic wave propagation and attenuation characteristics. A commercially available FE software “ABAQUS” was used. FE analysis reveals that acoustic leak noise can propagate up to 150 m before attenuating to the ambient noise level in water mains. |
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