High heat-flux sensor calibration: a monte carlo modeling
Murthy, A. V., Prokhorov, A. V. and Dewitt, D. P.
2004 Journal of Thermophysics and Heat Transfer, vol. 18, no. 3, pp. 333-341(9)
Murthy, A. V., Prokhorov, A. V. and Dewitt, D. P., (2004), "High heat-flux sensor calibration: a monte carlo modeling", Journal of Thermophysics and Heat Transfer, vol. 18, no. 3, pp. 333-341(9).
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 extension of the calibration to higher heat-flux levels requires placement the sensors inside the heated cavity under nearly hemispherical irradiation environment. The incident flux at the sensor location depends on the effective emissivity, which is a function of the combined cavity and sensor geometry, and the properties of the radiating surfaces. A scheme is presented to compute the effective emissivity for such measurement schemes by the use of the Monte Carlo technique. Typical results presented demonstrate the influence of the cavity wall surface emissivity and diffusity, nonuniform temperature distributions, and the sensor location on the calculated effective emissivity. The computations show that the optimum location for the sensor is at a distance of about one cavity radius from the cavity bottom. 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. The use of a reflecting shield to increase the effective emissivity is also investigated.