Progress on a Rayleigh Scattering Mass Flux Measurement Technique

Mielke-Fagan, Amy F.; Clem, Michelle M.; Elam, Kristie A.; Sverdrup, Jacobs; Hirt, Stefanie M.

doi:10.2514/6.2010-856

Cited by 2 publications

(1 citation statement)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Typical frequency drift observed in the Rayleigh work at NASA GRC is 5 -20 MHz, giving velocity errors of 2 -8 m/s. In many Rayleigh scattering experiments utilizing a CCD camera to detect the interference fringe pattern a small amount of incident laser light is spectrally analyzed along with the Rayleigh scattered light to provide a simultaneous reference of the incident laser signal, thereby eliminating the velocity measurement uncertainty attributable to laser frequency drift [11][12][13] . However, when this is done there is often significant overlap of the Rayleigh and reference fringes in the image because the frequency shift between the two signals is not large enough to distinctly separate the two fringes.…”

Section: Introductionmentioning

confidence: 99%

Improvement in Rayleigh Scattering Measurement Accuracy

Fagan

Clem

Elam

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

Self Cite

View full text Add to dashboard Cite

[Abstract] Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous velocity, density, and temperature measurements. The Fabry-Perot interferometer or etalon is a commonly employed instrument for resolving the spectrum of molecular Rayleigh scattered light for the purpose of evaluating these flow properties. This paper investigates the use of an acousto-optic frequency shifting device to improve measurement accuracy in Rayleigh scattering experiments at the NASA Glenn Research Center. The frequency shifting device is used as a means of shifting the incident or reference laser frequency by 1100 MHz to avoid overlap of the Rayleigh and reference signal peaks in the interference pattern used to obtain the velocity, density, and temperature measurements, and also to calibrate the free spectral range of the Fabry-Perot etalon. The measurement accuracy improvement is evaluated by comparison of Rayleigh scattering measurements acquired with and without shifting of the reference signal frequency in a 10 mm diameter subsonic nozzle flow.

show abstract

Section: Introductionmentioning

confidence: 99%