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High Heat-Flux Sensor Calibration: A Monte Carlo Modeling

Published

Author(s)

A V. Murthy, A Prokhorov, D P. DeWitt

Abstract

Conventional calibration of heat-flux sensors uses high-temperature blackbody radiation, and places the sensors away from the blackbody aperture. This approach limits the achievable calibration heat-flux to about 50 kW/m2. Recent interest in extending the calibration to higher heat-flux levels requires placing the sensors inside the heated cavity to ensure nearly hemispherical irradiation environment. Insertion of a cold sensor into the high-temperature cavity leads to significant deviation of conditions inside cavity from thermodynamic equilibrium. An effective emissivity based on the cavity-geometry, sensor size and position, distributions of optical characteristics and temperatures over all surfaces participating in radiative heat exchange need consideration. This paper addresses the issue of determining the effective emissivity for such measurement schemes using the Monte Carlo technique. By numerical modeling of the boundary comprising of the cool sensor and the blackbody cavity as a closed enclosure, the analysis calculates the effective emissivity variation for different locations of the sensor inside the cavity, wall emissivity, and non-uniform temperature distribution. The results of the numerical computation show that the optimum location for the sensor is at a distance of about one cavity radius from the cylindrical cavity base. The effective emissivity at this location has a high value even in the presence of a linear wall-temperature variation, and is relatively insensitive to the cavity-wall temperature gradient.
Proceedings Title
AIAA Thermophysics Conference
Volume
18
Issue
No. 3
Conference Dates
June 28-July 1, 2004
Conference Location
Undefined
Conference Title
Journal of Thermophysics and Heat Transfer

Keywords

blackbody, emissivity, heat-flux sensors, Monte Carlo method

Citation

Murthy, A. , Prokhorov, A. and DeWitt, D. (2004), High Heat-Flux Sensor Calibration: A Monte Carlo Modeling, AIAA Thermophysics Conference, Undefined (Accessed April 15, 2024)
Created June 30, 2004, Updated October 12, 2021