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  Products Glossary of Technical Terms  



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).

Lu, X., Winnik, M.A., “Luminescent Quenching by Oxygen in Polymer Films”.

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.