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TEMPERATURE SENSITIVE PAINT |
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High resolution, non-intrusive measurements of temperature and
heat transfer using temperature sensitive paint have been demonstrated by Liu
and Campbell. A typical TSP consists of
the luminescent molecule and an oxygen impermeable binder. The basis of the temperature sensitive paint
method is the sensitivity of the luminescent molecules to their thermal
environment. The luminescent molecule
is placed in an excited state by absorption of a photon. The excited molecule deactivates through the
emission of a photon. A rise in
temperature of the luminescent molecule will increase the probability that the
molecule will return to the ground state by a radiationless process. This process is known as thermal quenching
and is the basis of temperature sensitive paint. The temperature of the painted surface can be measured by
detecting the fluorescence intensity I(T) of the luminescent paint.
The luminescent intensity of the temperature sensitive paint at a
given point is not only a function of temperature.For practical applications of TSP spatial variations in
illumination, paint concentration, paint layer thickness, and camera
sensitivity will result in a variation in the detected luminescent intensity
from the test surface. These spatial
variations are eliminated by ratioing the luminescent intensity of the paint at
the unknown test condition (IT) with the luminescent intensity of
the paint at a known reference condition (Iref, Tref).
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Lu, X., Winnik, M.A.,
“Luminescent Quenching by Oxygen in Polymer Films”.
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Liu, T., Campbell, B.T., Burns, S.P.,
Sullivan, J.P., “Temperature- and Pressure-Sensitive Luminescent Paints in Aerodynamics”, Appl. Mech. Rev. v 50, n 4, 1997, 227-246.
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