2-D velocity and vorticity measurements with FLEET

Nathan D. Calvert, Arthur Dogariu, Richard B. Miles

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Femtosecond Laser Electronic Excitation Tagging (FLEET) was introduced recently (Michael, J., Edwards, M., Dogariu, A. and Miles, R., "Femtosecond laser electronic excitation tagging for quantitative velocity imaging in air," Applied Optics, Vol. 50, No. 5158, 2011) and is employed to measure two components of velocity and vorticity in over-expanded and under-expanded supersonic jets. Molecular nitrogen is dissociated in the focal region of a femtosecond laser pulse and recombines over tens of microseconds into an excited electronic state. The subsequent fluorescence of the tagged N2 is tracked with an intensified CCD camera as it propagates with the flow. Two approximately perpendicular lines are tagged and the displacement of the intersection and along the lines after a prescribed camera delay is used to extract linear and rotational velocity in the image plane. Simulations are performed to analyze the effect of signal-to-noise ratio, image resolution and laser parameters while assessing the uncertainty introduced from various data processing algorithms. Experimental data is obtained for no flow and in both circular and lenticular nozzle configurations at 2 and 5 μs camera delays. Averaged and single-shot velocity and vorticity are calculated employing a variety of techniques including Gaussian least-squares fit across the tagged line profile, one and two dimensional polynomial fits to image intensity and spatial cross-correlation for cross intersection displacement. A detailed statistical analysis based on a Bayesian framework reveals independent degrees of measurement uncertainty due to the experimental apparatus, data processing algorithms and both small and large-scale flow field fluctuations.

Original languageEnglish (US)
Title of host publicationAIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781624102875
DOIs
StatePublished - Jan 1 2014
EventAIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference - Atlanta, GA, United States
Duration: Jun 16 2014Jun 20 2014

Publication series

NameAIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference

Other

OtherAIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference
CountryUnited States
CityAtlanta, GA
Period6/16/146/20/14

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Mechanical Engineering

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  • Cite this

    Calvert, N. D., Dogariu, A., & Miles, R. B. (2014). 2-D velocity and vorticity measurements with FLEET. In AIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference (AIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference). American Institute of Aeronautics and Astronautics Inc.. https://doi.org/10.2514/6.2014-2229