Modeling of the thermal radiative behavior of rough coatings

Abstract 675 - Monte Carlo modeling of the thermal radiative behavior of rough coatings

Presented in the session Photothermal Techniques. Theory and Modeling at the 18th European Conference on Thermophysical Properties, Pau, France 31 Aug-4 Sep 2008
By:
Mr Hector Gomarta*+
Dr Benoit Rousseaua
Dr Domingos De Sousa Menesesa
Dr Patrick Echeguta

a CNRS Orléans
CEMHTI
Site Haute Température
1D avenue de la Recherche Scientifique
45071 cedex 02, France

*: Corresponding author
+: Presenting author

ABSTRACT:

Surface roughness plays a crucial role in the thermal radiative properties of industrial systems, such as infrared heaters, plate near blackbody references used to calibrate a pyrometric setup. Nevertheless literature usually reports radiative properties simulations only for several wavelengths. In this study, we focus on modeling emissivity over a wide IR-spectral range for surfaces either measured by profilometry or numerically rebuild.

Spectral Emittance of Ablation Chars, Carbon, and Zirconia to 3700 deg K

Hemispherical Spectral Emittance of Ablation Chars, Carbon, and Zirconia to 3700 deg K
Authors: R. G. Wilson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER

Abstract: The initial results of the application of special optical techniques to high-temperature emittance and reflectance studies of an ablation-material char and certain other refractory materials representative of those present in ablation residues formed during aerospace reentry operations are presented. Spectral hemispherical emittance and reflectance were determined with an image pyrometer integrated with an arc-imaging furnace for carbon, graphite, zirconia, and a phenolic-nylon ablation-material char at wavelengths from 0.37 micrometer to 0.72 micrometer for temperatures from 2100 deg K to 3700 deg K. The data obtained are compared with those of other investigations to the extent that the existence of comparable data permits. Surface-roughness properties of the materials studied were determined from measurements made with a light-section microscope. The dependence of the spectral hemispherical emittance of oxidized carbon at a wavelength of 0.65 micrometer on its surface-roughness properties was investigated experimentally and the emittance was found to be a linear function of the root-mean-square slope of the surface when the roughness is large compared with wavelength. p3

Limitations: APPROVED FOR PUBLIC RELEASE
Description: Technical note
Pages: 31
Report Date: MAR 65
Report Number: A107703