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Updated: Jul 14, 2026

The Measurement of Unsteady Surface Pressure Using a Remote Microphone Probe
Published on: December 3, 2016
Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics
Roger C Hart1, G C Herring, R Jeffrey Balla
1NASA Langley Research Center, Hampton, VA 23681, USA.
Abstract:
Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.
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