DEVELOPMENT OF A FIBEROPTIC PROBE FOR THERMOGRAPHIC PHOSPHOR MEASUREMENTS IN TURBINE-ENGINES

A laser-based system for remotely measuring the surface temperature of parts coated with thermographic phosphor (Y2O3:Eu) is described. The obtained temperature-decay lifetime calibration measurements and empir ical fits for Y2O3:Eu (4.52% Eu) over the temperature range 200-1000-d egrees-C are presented. In addition, the results of a proof-of-princip le test conducted on a stationary coupon coated with Y2O3:Eu immersed in an atmospheric-combustor, chamber are described. Furthermore, a des ign of a fiber optic probe for fluorescence decay lifetime measurement s within turbine engines is presented. A surface-damage threshold of a pproximately 3.5 J/cm2 (266 nm/4-6 ns pulse width) was measured for th e fused silica step-index optical fiber used.