Real-time Cavity Volumetry via Helmholtz Resonance Using Pressure Amplitude: Proof of Concept
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Authors
Barzegar, Mohammad Amin
Davies, Clive
Grafton, Miles
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Item type
Journal Article
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Springer
Abstract
Helmholtz resonance provides a well-established acoustic basis for determining volume via the resonance-frequency–volume relationship. However, frequency-tracking methods are typically too slow for dynamic measurements. We present an alternative physical model, the sound-pressure quality-factor (SPQF) model, which estimates volume in real time from cavity sound-pressure amplitude, avoiding frequency hunting. The model follows from the equations governing the driven, underdamped vibration of the port-air mass. The resonator is excited at its empty-cavity natural frequency with a single-tone drive; inserting a sample reduces the steady-state pressure amplitude, from which displaced volume is inferred. We validate the method with liquid and solid samples in 1-, 2-, and 3-L cavities and in a mechanically adjustable chamber under dynamic conditions. The approach achieved millilitre-level accuracy for solids and relative expanded uncertainty U, k = 2 < 0.1% of cavity capacity in static tests, and it tracked liquid discharge at ~ 15–20 Hz. On the mechanically variable resonator, SPQF tracked piston-driven volume changes for speeds up to 75 mm·s⁻1, delivering ~ 20 measurements in 1.5 s.Description
Keywords
51 Physical Sciences, 40 Engineering, 5103 Classical Physics, Bioengineering, 02 Physical Sciences, 09 Engineering, Acoustics, Helmholtz resonance, Cavity volumetry, Sound pressure quality factor (SPQF)
Source
Acoustics Australia, ISSN: 0814-6039 (Print); 1839-2571 (Online), Springer, 1-19. doi: 10.1007/s40857-026-00385-3
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