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Small leaks are hard to detect by transient-based leakage detection methods based on classical waterhammer theory because the leak induces small frequency shifts in the probing transient wave. This shift becomes even smaller as the frequency of the probing wave increases. Surprisingly, simple experiments conducted by our team demonstrate that small leaks induce a significant shift in the probing transient wave once the frequency is increased high enough to excite radial wave modes.
This research project aims to understand the interaction between the leak and the three-dimensional (radial modes) probing waves in a pipe system. Some of the project's objectives are:
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Theoretically and experimentally examine the leak-wave interaction over the frequency range from 5 to 50 kHz.
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Understand the physical mechanism that explains the significant frequency shift of the wave by the leak when the Helmholtz number is of order one.
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Assess the validity for using the standard orifice relation to represent the leak and, if necessary, to guide the formulation of a new, frequency-dependent leak relation.
With the results of this research project, we expect to:
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Provide insights that explain the unexpected significant shift that occurs when the Helmholtz number is of order one.
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Lead to the derivation of a leak-impedance relation valid for three-dimensional wave conditions.