Optical Methods for Data Processing in Heat and Fluid Flow

10

Thermographic Phosphor Thermometry – Recent Developments for Applications in Gas Turbines

J P Feist, A L Heyes, K L Choy, and J R Nicholls

Abstract

This Chapter provides a review of the research conducted to date by the authors concerning the development of the thermographic phosphor thermometry technique for application in gas turbine combustors and high-temperature regions of the turbine. In such regions protection of components from excess heating is critical and achieved by a combination of cooling air and protective ceramic coatings. Temperature measurement is an integral part of the development process for cooling and insulation schemes but the application of conventional techniques is problematic. Thermographic phosphors consist of a ceramic host matrix with a lanthanide ion dopant. When illuminated with UV light they exhibit phosphorescence which is temperature dependent by virtue of variations in the relative intensities of distinct emission lines or in the time constant of the exponential decay which occurs once excitation has ceased. The authors have surveyed a range of known phosphors and identified YAG:Dy, YAG:Tb, and Y₂O₃:Eu as being appropriate for use in turbines. A calibration of the temperature response of these phosphors is presented and shows that overall they have a dynamic range extending to in excess of 1200 °C and allow measurement with a precision which can be better than ±1 °C.

The authors have proposed the concept of a smart thermal barrier coating ...