High Heat Flux Sensors Calibration in a Cooled Enclosure.
High Heat Flux Sensors Calibration in a Cooled
Murthy, A. V.; Tsai, B. K.; Saunders, R. D.
NIST SP 971; August 2001.
NIST SP 971: "Collected Reports and Publications by the
National Institute of Standards and Technology on Heat
Flux Gage Calibration and Usage." AND Instrumentation
Symposium, 45th International. Proceedings. Sponsored
by Aerospace Industries Division and Test Measurement
division of ISA. May 2-6, 1999, Albuquerque, NM, 91-100
Available from:For More Information on NIST SP 971 visit: WEBSITE:
heat flux; sensors; enclosures; calibrating; absolute
technique; transfer technique
This paper reports of an experimental study of
calibrating heat flux sensors using a spherical
blackbody and mounting the sensor inside a cooled outer
sleeve protruding from the radiating aperture.
Measurements with a Gardon-type heat flux sensor show
that this arrangement may not necessarily lead to
improved absolute calibrations at all locations inside
the cooled sleeve. Large variations in measured
responsivities were observed depending on the distance
of the gage from the radiating aperture of the
blackbody. This discrepancy is suspected to be due to
the induced circulation effect of the furnace hot gas
extending up to the gage location. It is demonstrated
that the discrepancy can be reduced by providing
suitable venting around the gage holder instead of
testing in a fully closed mode. However, transfer
calibration of the same Gardon gage with a reference
standard Schmidt-Boelter gage gave good agreement for
gage locations ranging form inside the furnace to the
cooled enclosure. Limitations of the testing in the
cooled enclosure and possibilities for further
improvement are discussed.