Towards an Improved Lifing Methodology for Thermocouple Probes Used in Gas Turbines

Abstract

The reliability of temperature probes in gas turbines is dependent on their capability to withstand the harsh environment they experience when installed in an engine. The severe conditions sensors experience during operation requires the use of appropriate methodologies to assess their life. During the ALPHET project the University of Cambridge and Esterline Advanced Sensors have been working on developing an advanced lifing methodology: in order to predict the life of thermocouple probes used in gas turbines, this combines accelerated laboratory tests based on the salt deposition method, combustor rig tests, metallurgical analysis of probes returned after engine service and information extracted from their associated temperature data acquired during their long term operation in aero gas turbines. The work included analysis of materials used in current temperature probes and investigation of advanced materials for future thermocouple sensors that will work at temperatures higher than today’s probes. This paper will summarise the main features of the improved lifing methodology and the challenges associated with the use of complex engineering data obtained from engines.