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Evaluation of miniature single-wire sheathed thermocouples for turbine blade temperature measurementChromel Alumel thermocouples were used, with sheath diameters of 0.15 and 0.25 mm. Tests were conducted at temperatures ranging from 750 to 1250 K. Both steady state and thermal cycling tests were performed for times up to 200 hours. Initial testing was performed in a low velocity gas stream for long time periods using a Meker-type burner. Additional testing was done in a high velocity gas stream for short time periods using a hot gas tunnel and also in a J75 jet engine. A total of eleven 0.15 mm diameter thermocouples and six 0.25 mm diameter thermocouples were tested. Drift rates up to 2.5% in 10 hours were observed. Photomicrographs show that this design is near the limit of miniaturization based on present manufacturing capabilities. Results indicate that the effects of miniaturization on reliability and accuracy must be considered when choosing thermocouples for a particular application.
Document ID
19790019309
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Hollanda, R. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
June 1, 1979
Subject Category
Instrumentation And Photography
Report/Patent Number
E-068
NASA-TM-79173
Accession Number
79N27480
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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