CUED Publications database

Measurements of thermal radiation in ultralight metal foams with open cells

Zhao, CY and Lu, TJ and Hodson, HP (2004) Measurements of thermal radiation in ultralight metal foams with open cells. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 218. pp. 1297-1308. ISSN 0954-4062

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Abstract

Highly porous ultralightweight cellular metal foams with open cells have attractive mechanical, thermal, acoustic and other properties and are currently being exploited for high-temperature applications (e.g. acoustic liners for combustion chambers). In such circumstances, thermal radiation in the metal foam becomes a significant mechanism of heat transfer. This paper presents results from experimental measurements on radiative transfer in Fe-Cr-Al-Y (a steel-based high-temperature alloy) foams having high porosity (95 per cent) and different cell sizes, manufactured at low cost from the sintering route. The spectral transmittance and reflectance are measured at different infrared wavelengths ranging from 2.5 to 50 μm, which are subsequently used to determine the extinction coefficient and foam emissivity. The results show that the spectral quantities are strongly dependent on the wavelength, particularly in the short-wavelength regime (less than 25 μm). While the extinction coefficient decreases with increasing cell size, the effect of cell size on foam reflectance is not significant. When the temperature is increased, the total extinction coefficient increases but the total reflectance decreases. The effective radiative conductivity of the metal foam is obtained by using the guarded hot-plate apparatus. With the porosity fixed, the effective radiative conductivity increases with increasing cell size and increasing temperature. © IMechE 2004.

Item Type: Article
Uncontrolled Keywords: Open cells Thermal radiation Ultralight metal foams
Subjects: UNSPECIFIED
Divisions: Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:51
Last Modified: 30 Nov 2014 20:45
DOI: