ISA107.2, Thermographic Phosphor

Purpose and Scope: The higher temperatures of the latest engine designs require the use of Thermal Barrier Coatings (TBC) to allow the cooling air being pumped through the blades to be minimized and thereby improve the efficiency of the engine. The use of TBCs, however, virtually prevents the use of pyrometry to measure blade and vane temperatures, since the TBCs are approximately 4 times less emissive than metal surfaces, and about 4 times more reflective of the fireball radiation being emitted immediately upstream of the turbine in the combustor.

Thermographic Phosphors have been used in a number of other high temperature applications and hold significant potential for solving our component temperature measurement problems in the engine. Again, no measurement standards currently exist for the use of Thermographic Phosphors. Through the use of Thermographic Phosphors, temperatures can be determined from pulsed-illumination-induced fluorescence of thin phosphor coatings applied to turbine engine surfaces of interest. In a similar fashion, suitable composites of Thermographic phosphors integrated with thermal barrier coatings (TBC) can fluoresce and yield temperature and other indications of TBC health.

The basic components consist of an excitation source (usually a laser or an LED), an optical probe that provides for illumination of the coating and collection of the fluorescence, the coating and the method for applying it, a data acquisition system, and a data analysis protocol.

Standards for comparing the various approaches and defining appropriate benchmarks are needed. Standardizing the definitions of coating durability, fluorescence efficiency, temperature range, temperature sensitivity and methods for establishing these characteristics, as well as establishing, a set of standards or best practices for the other components of a system are needed. Establishing Standards for Thermographic Phosphors will be a major benefit to both aircraft and power generation engine manufacturers and to sensor vendors alike.

The ISA107.2 subcommittee is currently working on a draft under the direction of Chairman Steve Allison. For more information, please contact Charley Robinson - crobinson@isa.org

Marcus Alden Information Member Lund Institute of Technology Phone: 46 46 2227657 Fax: 46 46 2224542	Stephen Allison Voting Member Chair Emerging Measurements Co Phone: (865) 256-5485
David Beshears Information Member Emerging Measurement Co Phone: (865) 765-3864	Tom Bonsett Information Member Rolls-Royce Allison Phone: (317) 230-3448
Jan Brubach Information Member Center of Smart Interfaces Phone: +49-6151-16-2502	Jeffrey Eldridge Information Member NASA Glen Research Center Phone: (216) 433-6074 Fax: (216) 977-7150
Jorg Feist Information Member Southside Thermal Sciences Ltd Phone: +44 0207 5943564	George Gillies Information Member University of Virginia Phone: (435) 924-7634
Bauke Heeg Information Member Lumium Phone: 011 +31 58 8431 782	Andrew Heyes Information Member Imperial College London Phone: +44 0 20 7494 7044
William Hollerman Information Member	Tom Jenkins Information Member
Konstantinos Kontis Information Member University of Manchester Phone: +44 0 161 306 5751	Mattias Richter Information Member Lund Institute of Technology Phone: 46 046 2224656
Charley Robinson Staff Contact ISA Phone: (919) 990-9213 Fax: (919) 549-8288	Greg Walker Information Member Vanderbilt Univ Phone: (615) 343-6959
Joseph Weiss Managing Director Applied Control Solutions LLC Phone: (408) 253-7934 Fax: (408) 253-7974	Simon Wilson Information Member Gastops Ltd Phone: (613) 744-6215 x118 Fax: (613) 744-8846