Simultaneous Quantitative Imaging of Temperature and H₂O/CH₂O Concentration by Using LAS-Fused Nd-YAG Laser-Induced Fluorescence

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Abstract
A planar laser induced fluorescence (PLIF) using the third harmonic of the Nd-YAG laser at 355 nm is employed to visualize temperature and H 2 O/CH 2 O concentration distributions inside flames. Laser Absorption Spectroscopy (LAS) is employed for initial images of temperature and H 2 O concentration, and the measured absorption offers constraints to update temperature and H 2 O concentration images. A chemical reaction kinetics model based on ethanol combustion mechanisms is established, offering the production rate of H 2 O and CH 2 O, thereby bridging PLIF and LAS. The images of temperature and CH 2 O/H 2 O concentration is produced iteratively for quantitative imaging of the flame cross-section. A flame fueled with ethanol vapor was used and images of temperature, H 2 O concentration and CH 2 O concentration were given. Comparisons with thermocouples, the temperature difference was found to be no more than 40 K. The images of H 2 O and CH 2 O concentrations detailed the area of incomplete combustion within the flame and its temporal variations. Relative deviations from experiment results to the ideal values are respectively 3.05 % and 5.34 % for H 2 O and CH 2 O.
Funding Information
  • National Natural Science Foundation of China (61827802)
  • National Natural Science Foundation of China (62031002)
  • National Natural Science Foundation of China (U2241259)

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