Laser-induced Phosphorescence for Surface Thermometry in the Afterburner of an Aircraft Engine

In the present work, surface thermometry using a method based on the spectroscopy of inorganic luminescent
material was applied in the afterburner of a full-size aircraft jet engine. The technique uses laser-induced emission
from thermographic phosphors for nonintrusive remote temperature diagnostics in combustion applications with
high sensitivity and accuracy. A phosphor material having suitable temperature sensitivity in the expected
temperature range was applied to the surface of interest in the engine afterburner. Phosphorescence radiation was
generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser. The resulting signal was detected with a
photomultiplier tube and phosphorescence lifetime decay curves were recorded for various engine loads, including
operation of the afterburner. By analyzing the phosphorescence decay, temperature data were acquired through
implementation of a regression equation extracted from well-defined calibration measurements on the phosphor
used. Quantitative temperature data recorded with a repetition rate of 10 Hz are presented. The laser-induced
phosphorescence technique for surface thermometry has proven its applicability in the extremely harsh environment
prevailing inside and next to a jet engine operating at full load.