Infrared thermography as applied to film cooling of gas turbine components

Infrared thermography has increasingly gained importance in generic as well as in real engine film cooling investigations. Given the availability of optical access today's infrared camera systems allow an in-depth understanding of heat transfer processes in hot-gas ducting components of gas turbine engines based on a very detailed analysis of according surface temperatures. Although considerable progress has been achieved in the past, concerning both hardware and software, quantitative infrared analyses still require an in situ calibration. Based on the fundamentals of radiative heat transfer a correction method accounting for the specific boundary conditions accompanied by measurements in hot-gas ducts will be described. Two examples of film cooling investigations, contoured single-hole coolant ejection and full-coverage film cooling, will be presented as typical applications of in situ calibrated infrared thermography.