C1.2 - A Spectral Approach to Acoustic Absorption Measurement

Event
AMA Conferences 2017
2017-05-30 - 2017-06-01
Nürnberg, Germany
Band
Proceedings Sensor 2017
Chapter
C1 - Acoustic Methods I
Author(s)
L. Claes, R. Chatwell, J. Vrabec, B. Henning - Paderborn University (Germany)
Pages
304 - 309
DOI
10.5162/sensor2017/C1.2
ISBN
978-3-9816876-4-4
Price
free

Abstract

Next to the sound velocity, the absorption coefficient of acoustic waves in fluids is an important thermodynamic property. Although measurements of acoustic absorption have been conducted in the past, most of them negate the influence of parasitic dissipative effects or rely on either analytical or empirical compensation. A typical method for measuring acoustic absorption is to determine the decline of the acoustic signal amplitude as the wave propagates through the medium. We present an alternative approach, by utilizing that acoustic waves experience dispersive effects in absorbing media. It is known
that acoustic absorption in fluids increases with the squared frequency of the acoustic wave. On this basis, we deduce an analytic expression that links the decline of the spectral centroid (center frequency) of the acoustic signal to the medium’s absorption coefficient. The results are verified using a simulation environment that is based on finite differences.

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