Abstract
A method for quantifying and correcting background signals due to back reflections in planar laser-induced fluorescence (PLIF) images is presented. It is shown that reflections of fluorescence off back walls can falsely elevate the signal in a PLIF image. A model for these back reflections is presented, and this model is used to generate a kernel with which images are corrected via direct inverse filtering. The correction method is demonstrated on PLIF images acquired in a static cell: first, background signals are quantified in a static cell by blocking portions of the beam and measuring the fluorescence signal in regions of the image where there is no fluorescence; second, a background correction kernel is generated by recovering the uncontaminated signal via direct inverse filtering. Finally, the method is extended to correct PLIF imaging of supersonic flowfields where large signal gradients exist across a shock wave. The correction is shown to improve agreement between measured expected signal levels on the stagnation line of supersonic flow around a 2D blunt body.
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Acknowledgments
This paper is based upon work supported by the Air Force Office of Scientific Research (AFOSR) and by the Department of Energy under the Predictive Science Academic Alliance Program (PSAAP) at Stanford University, award number DE-FC52-08NA28614. V. A. Miller is supported by the Claudia and William Coleman Foundation Stanford Graduate Fellowship. The author would also like to thank M Gamba, MG Mungal, and RK Hanson for their guidance.
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Miller, V.A. Quantifying and correcting for contamination of PLIF images due to background signals. Exp Fluids 54, 1566 (2013). https://doi.org/10.1007/s00348-013-1566-7
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DOI: https://doi.org/10.1007/s00348-013-1566-7