SEDL / STP / STP1427-EB / STP10948S

Calibration of a Heat Flux Sensor up to 200 kW/m² in a Spherical Blackbody Cavity

Murthy, AV
President, Aero-Tech, Inc., Hampton, VA

Tsai, BK
Physical Scientist, Optical Technology Division, NIST, Gaithersburg, MD

Saunders, RD
President, Saunders Enterprises, Gaithersburg, MD

Pages: 16    Published: Jan 2003

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Abstract

This paper presents the results of a comparative study of narrow view-angle and wide view-angle calibrations of a water-cooled Schmidt-Boelter heat-flux sensor. The narrow view-angle calibration, up to a heat flux level of 50 kW/m², was conducted using the 25 mm Variable Temperature Blackbody (VTBB) facility. An electrical substitution standard was used as a transfer standard to determine the flux level at the sensor plane. The wide view-angle calibration was conducted by placing the sensor inside the radiating cavity of a spherical blackbody. The calibration in the spherical blackbody is based on the heat-flux derived from the Stefan-Boltzmann equation using the blackbody temperature measured from a type-S thermocouple. The calibration covered an extended range from 50 kW/m² to 200 kW/m². Results of the calibration of the heat-flux sensor using the two different techniques are presented. A discussion of the problems associated with calibrating sensors at high heat-flux levels by inserting the sensor inside a blackbody cavity is also presented.