A probe has been designed at the NASA Lewis Research Center and built for use in oxidizing atmospheres to temperatures exceeding 2000 °C. Conventional platinum-based probes are useable to only about 1500 °C. In contrast, this new probe consists of a tungsten-rhenium thermocouple (useable to 2300 °C, but very susceptible to oxidation at high temperatures) surrounded by a beryllium oxide tube. The inside of this tube is filled with argon to protect the thermocouple from oxidation. Beryllium oxide was chosen as the tube material because of its high melting point, good electrical properties at high temperatures, and excellent resistance to thermal shock.
Two probes were tested at NASA Lewis. The first survived several
cycles (a total of roughly 4 hours) between room temperature and
about 2040 °C, before being destroyed by debris in the test section.
The second suffered mechanical damage during installation. After
testing, the design was revised to make it more rugged without
compromising the thermal properties of the probe.
Development of this probe is part of a strategy to explore the
use of conventional probes as well as optical probes to measure
gas temperatures within test combustors.
Lewis contact: Gustave C. Fralick, (216) 433-3645, Gustave.C.Fralick@grc.nasa.gov
Author: Gustave C. Fralick
Headquarters program office: OA
Previous articleLast updated May 5, 1997
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