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Proceedings Paper

Infrared attenuation analysis of lognormal distribution water mist in the atmosphere windows
Author(s): Zhong-wei Chen; Xin-gang Liang; Xiang-hua Xu; Hong-bin Wang; Ling-jiang Zhang
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Paper Abstract

Because of high infrared attenuation, water mist (or fog) are widely used in fire prevention and heat radiation protection etc. However, the theoretical analysis and calculation of water mist about infrared attenuation are not easy due to parameters that complicate the transport process, such as multi-scattering in the water mist, distribution of droplets, concentration of droplets and water optical constant in the infrared atmosphere windows, etc. There are several methods to calculate the water mist infrared attenuation, for example, Monte-Carlo method (MCM), independent scattering method (ISM) and solo mean diameter method (SMDM). These methods have different accuracy and complicacy. Theoretically, MCM should be more precision and complicated than the other methods but no report on the comparisons between these methods is found by the authors. The present article studies the spectral transmittance of water mist with different concentration and different thickness using MCM and Mie theory, since spectral transmittance of water mist in the infrared atmosphere windows with lognormal distribution is important data for infrared attenuation analysis. At the same time, the transmittance of the same water mist was calculated with ISM and SMDM and the results of MCM were compared with those of ISM and SMDM. It is clearly indicates that the ISM is accurate when the droplet concentration is less than 320 droplets/cm3, the SMDM is accurate when the droplet concentration was less than 300 droplets/cm3, with variance 2 and mean diameter 8μm lognormal distribution. When the mean diameter of water mist is below 8μm, ISM and SMDM are applicable with higher mist concentration. The ISM and SMDM is valuable for engineering calculation about water mist infrared attenuation, when the mist concentration is not high enough.

Paper Details

Date Published: 4 August 2009
PDF: 10 pages
Proc. SPIE 7383, International Symposium on Photoelectronic Detection and Imaging 2009: Advances in Infrared Imaging and Applications, 738337 (4 August 2009); doi: 10.1117/12.834517
Show Author Affiliations
Zhong-wei Chen, Tsinghua Univ. (China)
Naval Academy of Armament (China)
Xin-gang Liang, Tsinghua Univ. (China)
Xiang-hua Xu, Tsinghua Univ. (China)
Hong-bin Wang, Naval Academy of Armament (China)
Ling-jiang Zhang, Naval Academy of Armament (China)

Published in SPIE Proceedings Vol. 7383:
International Symposium on Photoelectronic Detection and Imaging 2009: Advances in Infrared Imaging and Applications
Jeffery Puschell; Hai-mei Gong; Yi Cai; Jin Lu; Jin-dong Fei, Editor(s)

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