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.
© 2007 Optical Society of America
Instrumentation, Measurement, and Metrology
Original Manuscript: February 15, 2007
Revised Manuscript: April 11, 2007
Manuscript Accepted: April 12, 2007
Published: June 5, 2007
Roger C. Hart, G. C. Herring, and R. Jeffrey Balla, "Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics," Opt. Lett. 32, 1689-1691 (2007)