Dynamic Measurement of Gas Flow using Acoustic Resonance Tracking

Published

March 21, 2023

Author(s)

Jodie Gail Pope, Keith A. Gillis, James W. Schmidt

Abstract

We measured gas flows exiting large, un-thermostated, gas-filled, pressure vessels by tracking the time-dependent pressure P(t) and resonance frequency fN(t) of an acoustic mode N of the gas remaining in each vessel. This is a proof-of-principle demonstration of a gas-flow standard that uses P(t), fN(t), and literature values of the speed-of-sound to determine a mode-weighted average temperature Tj of the gas remaining in a pressure vessel. Therefore, the vessel is a calibrated source of gas flow. To track fN(t) while flow work rapidly changes the gas's temperature, we sustained the gas's oscillations using positive feedback. Feedback oscillations track Tj with a response time of order 1/fN. In contrast, driving the gas's oscillations with externally-determined frequencies yields much slower response times of order Q/fN. (For our pressure vessels, Q 104.) We tracked fN(t) of radial modes in a spherical vessel (1.85 m3) and of longitudinal modes of a cylindrical vessel (0.3 m3) during gas flows ranging from 0.24 g/s to 12.4 g/s to determine the mass flows with a standard uncertainty of 0.51 %. We discuss the challenges in tracking of fN(t) and plans to reduce the uncertainties.

Citation

Review of Scientific Instruments

Volume

94

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0143819

Local Download

Keywords

Flow, acoustic, Self-oscillation, standard

Citation

Pope, J. , Gillis, K. and Schmidt, J. (2023), Dynamic Measurement of Gas Flow using Acoustic Resonance Tracking, Review of Scientific Instruments, [online], https://doi.org/10.1063/5.0143819, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935707 (Accessed April 26, 2024)