Modeling the effects of surface roughness on the emissivity of aluminum alloys

This study explores the relationship between the emissivity of aluminum alloy surfaces and surface roughness. Two methods are discussed which yield good overall predictions of the emissivity of rough surfaces. One method consists of using a mathematical multispectral radiation thermometry (MRT) model for the emissivity and determining both the surface temperature and the empirical constants in the emissivity model from radiance measurements. This method requires new emissivity constants to be determined for each surface topography. This study also presents an alternative method for determining the emissivity of rough surfaces. This method relies on determining the emissivity characteristics of a single reference surface and inferring the emissivity of any other rough surface of the same material by relating a surface roughness function (determined by surface topography instrumentation) of the rough surface to that of the reference surface. Using data for AL 7075 with various degrees of surface roughness, this method is shown to yield better accuracy than the first method.

[1]  R. Birkebak,et al.  Effects of Roughness of Metal Surfaces on Angular Distribution of Monochromatic Reflected Radiation , 1965 .

[2]  A preliminary investigation of the bidirectional spectral reflectance of V-grooved surfaces. , 1966, Applied optics.

[3]  R. O. Buckius,et al.  A statistical model of wave scattering from random rough surfaces , 2001 .

[4]  J. Richmond,et al.  Thermal Radiative Properties of Materials , 2007 .

[5]  P. B. Coates,et al.  Multi-Wavelength Pyrometry , 1981 .

[6]  M. Pinar Mengüç,et al.  Thermal Radiation Heat Transfer , 2020 .

[7]  Chang-Da Wen,et al.  Emissivity characteristics of roughened aluminum alloy surfaces and assessment of multispectral radiation thermometry (MRT) emissivity models , 2004 .

[8]  Chang-Da Wen,et al.  Experimental investigation of emissivity of aluminum alloys and temperature determination using multispectral radiation thermometry (MRT) algorithms , 2002 .

[9]  R. Hering,et al.  Apparent radiation properties of a rough surface , 1969 .

[10]  H. E. Bennett,et al.  Relation between Surface Roughness and Specular Reflectance at Normal Incidence , 1961 .

[11]  J. Ogilvy Wave scattering from rough surfaces , 1987 .

[12]  M. Brewster Thermal Radiative Transfer and Properties , 1992 .

[13]  R. A. Dimenna,et al.  Regions of validity of the geometric optics approximation for angular scattering from very rough surfaces , 1996 .

[14]  R. Birkebak,et al.  Effects of large pyramidal surface roughness on spectral directional emittance , 1977 .

[15]  Optical surface roughness and slopes measurements with a double beam spectrophotometer , 1974 .

[16]  Yildiz Bayazitoglu,et al.  International Journal of Heat and Mass Transfer , 2013 .

[17]  M. Modest Radiative heat transfer , 1993 .

[18]  S. Rice Reflection of electromagnetic waves from slightly rough surfaces , 1951 .

[19]  Quantifying specular approximations for angular scattering from perfectly conducting random rough surfaces , 1994 .

[20]  H. E. Bennett Specular Reflectance of Aluminized Ground Glass and the Height Distribution of Surface Irregularities , 1963 .

[21]  J. O. Porteus Relation between the Height Distribution of a Rough Surface and the Reflectance at Normal Incidence , 1963 .

[22]  R. O. Buckius,et al.  The geometric optics approximation for reflection from two-dimensional random rough surfaces , 1998 .