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Department of Mechanical Engineering & Applied Mechanics
University of Michigan, Ann Arbor, MI 48109
Abstract-
Many industrial and domestic machines use or convey pressured gases or
liquids. Leak testing is a critical manufacturing quality-control process
because unintended leaks may be detrimental to consumers, manufacturers,
and the environment. This presentation describes a technique for leak
detection and localization that is based on recordings of photoacoustic
sounds and passive acoustic time reversal. Photoacoustic sounds are
generated by a raster-scanned carbon-dioxide laser beam and the gas cloud
that forms in the immediately vicinity of a calibrated leak of
sulfur-hexafluoride. Experimental results from a four-microphone array
with a signal bandwidth from 3 kHz to nearly 100 kHz are presented. These
results show that leaks with volume flow rates less than 1 cubic centimeter
per day can be remotely localized to within a few millimeters on a line
0.45 m long located 0.4 m away from the microphones.
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