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Application of structured illumination to gas phase thermometry using thermographic phosphor particles: a study for averaged imaging.
- Source :
- Experiments in Fluids; Jul2017, Vol. 58 Issue 7, p1-15, 15p
- Publication Year :
- 2017
-
Abstract
- Structured laser illumination planar imaging (SLIPI) is combined with gas phase thermometry measurements using thermographic phosphor (TGP) particles. The technique is applied to a heated jet surrounded by a coflow which is operated at ambient temperature. The respective air flows are seeded with a powder of BaMgAlO:Eu (BAM) which is used as temperature-sensitive gas phase tracer. Upon pulsed excitation in the ultraviolet spectral range, the temperature is extracted based on the two-color ratio method combined with SLIPI. The main advantage of applying the SLIPI approach to phosphor thermometry is the reduction of particle-to-particle multiple light scattering and diffuse wall reflections, yielding a more robust calibration procedure as well as improving the measurement accuracy, precision, and sensitivity. For demonstration, this paper focuses on sample-averaged measurements of temperature fields in a jet-in-coflow configuration. Using the conventional approach, which in contrast to SLIPI is based on imaging with an unmodulated laser light sheet, we show that for the present setup typically ~40% of the recorded signal is affected by the contribution of multiply scattered photons. At locations close to walls even up to 75% of the apparent signal is due to diffuse reflection and wall luminescence of BAM sticking at the surface. Those contributions lead to erroneous temperature fields. Using SLIPI, an unbiased two-color ratio field is recovered allowing for two-dimensional mean temperature reconstructions which exhibit a more realistic physical behavior. This is in contrast to results deduced by the conventional approach. Furthermore, using the SLIPI approach it is shown that the temperature sensitivity is enhanced by a factor of up to ~2 at ~270 °C. Finally, an outlook towards instantaneous SLIPI phosphorescence thermometry is provided. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 07234864
- Volume :
- 58
- Issue :
- 7
- Database :
- Complementary Index
- Journal :
- Experiments in Fluids
- Publication Type :
- Academic Journal
- Accession number :
- 123411188
- Full Text :
- https://doi.org/10.1007/s00348-017-2364-4