Thermographic phosphor thermometry for film cooling studies in gas turbine combustors

Abstract

The paper describes the application of thermographic phosphors for surface temperature measurements in gas turbine combustors and on surrounding components. Thermographic phosphors enable many of the problems associated with the application of conventional thermometry techniques in a combustion environment to be overcome. They consist of a ceramic host matrix with a lanthanide ion dopant. When illuminated with UV light, they exhibit luminescence 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 that occurs once excitation has ceased. The authors have calibrated the response of a range of phosphors and demonstrated that a useful dynamic response exists up to at least 1400±C. Furthermore, to demonstrate the utility of the technique, surface temperatures have been measured over a small region within a model gas turbine combustor. In this region the temperature distribution was measured with an estimated uncertainty of ±10 K, with the absolute temperature values confirmed by thermocouple measurements within the experimental uncertainties of this technique.