Determination of surface normal temperature gradients using thermographic phosphors and filtered Rayleigh scattering

J. Bruebach, Johan Zetterberg, Alaa Omrane, Zhongshan Li, Marcus Aldén, A. Dreizler

Research output: Contribution to journalArticlepeer-review

46 Citations (SciVal)

Abstract

Wall temperature as well as the temperature distribution within or close-by the boundary layer of an electrically heated axisymmetric jet impinging on a flat plate were monitored to deduce wall-normal temperature gradients. The radial surface temperature profile of the plate was determined by coating it with thermographic phosphors (TPs), materials whose phosphorescence decay time is dependent on their temperature. The TP was excited electronically by a frequency-tripled Nd:YAG laser (355 nm) and the temporal decay of the phosphorescence intensity was measured zero-dimensionally by a photomultiplier tube. In this case the 659-nm emission line of Mg3F2GeO4:Mn was monitored. The non-intrusive measurement of gas temperatures near the surface was performed two-dimensionally by filtered Rayleigh scattering (FRS). A tunable frequency-tripled single-longitudinal-mode alexandrite laser beam at 254 nm was formed into a light sheet pointing parallel to the surface. The scattered light was imaged through a very narrow linewidth atomic mercury filter onto an intensified charged coupled device (ICCD). The elastic stray light from surfaces was strongly suppressed, whereas Doppler-broadened light was detected. Thermographic phosphors proved to be reliable for the measurement of surface temperatures. Dependent on the specific experimental conditions, problems appeared with signals interfering with the FRS radiation close-by the surface. Results and challenges of this approach are discussed.
Original languageEnglish
Pages (from-to)537-541
JournalApplied Physics B
Volume84
Issue number3
DOIs
Publication statusPublished - 2006

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics

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