[2C2] Non-invasive characterisation of gas using acoustic resonance
Z Surujon, J Ashkenazy, E Mor, D Charutz and N Eldad
Soreq Nuclear Research Center, Israel
The authors present a novel technique for characterising gas inside vessels such as containers and pipes without requiring any physical access to the interior, by measuring the speed of sound in the gas using acoustic resonance. This method involves tapping on the vessel and recording the response using an accelerometer attached to the outer surface. Despite a strong background signal due to vibrations of the vessel, it is shown that resonance peaks of the gas are detectable in the spectrum. Their frequencies depend only on the shape of the enclosure and the speed of sound in the gas. Hence, the latter may be obtained from the detected resonance frequencies as long as the geometry is known. The accuracy of this method is typically of the order of a few permilles and is dominated by uncertainties in the geometry and spectral resolution. The dependence of the speed of sound in gases on the molecular mass and temperature renders this method useful for distinguishing different gases and detecting impurities, as well as for measuring the gas temperature.
