A novel laser-induced fluorescence technique has been developed for measuring the surface temperature of reacting and nonreacting materials. The technique involves seeding the material to be examined with a temperature-sensitive phosphor (Dy:Y AG) and monitoring the laserinduced fluorescence of the phosphor to determine the temperature. The Dy:Y AG phosphor displays a temperature sensitivity in the range 300-1700 K, The technique has been applied to both reacting and nonreacting surfaces under laser excitation, allowing temperature and temporal-history profiles to be determined.

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The formation of bulk and surface insolubles in a Jet A fuel during a single pass through heated stainless-steel tubes has been studied. Low temperature and low flow rates were utilized to produce near-isothermal conditions. In a second series of experiments, depletion of oxygen in the fuel saturated with respect to room-temperature air was measured under identical isothermal conditions. At a wall/bulk-fuel temperature of 185°C, rates of surface deposition and oxygen depletion were correlated; the maximum in the surface-deposition rate was found to occur after the Jet A fuel was stressed sufficiently that the dissolved oxygen was totally consumed. Results are discussed in terms of the autoxidation of the Jet A fuel and the concurrent production of deleterious bulk and surface insolubles.

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