Comparison of scattering behaviour for spherical and non-spherical particles in pulverized coal combustion

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• 作者：Tim Gronarz^a ; ^{info@wsa.rwth-aachen.de" class="auth_mail" title="E-mail the corresponding author} ; ; Matthias Schnell^a ; Christoph Siewert^b ; Lennart Schneiders^b ; Wolfgang Schr&ouml ; der^b ; Reinhold Kneer^a
• 关键词：Mie-theory ; Scattering ; Absorption ; T-Matrix ; Sphericity ; Particle orientation distribution ; DNS
• 刊名：International Journal of Thermal Sciences
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：111
• 期：Complete
• 页码：116-128
• 全文大小：1255 K

文摘

In numerical simulations of coal combustion processes, particle-radiation interaction is often described by Mie-theory. An important modeling assumption in Mie-theory is the sphericity of the particles. The aim of this study is to investigate the validity of the sphericity assumption. Therefore, the T-Matrix method is applied to calculate the scattering and absorption properties of non-spherical particles and to compare these with results from Mie-theory. Three types of non-spherical particles are considered: prolate, oblate, and Chebychev-type particles. The scattering and absorption properties are averaged over a particle size distribution, the incident radiation profile, and for non-spherical particles a particle orientation distribution.

The calculations reveal a deviation in scattering and absorption efficiencies below 10 % due to non-sphericity for all particles. For the scattering phase function, the deviation is on the order of 10 %. It strongly varies depending on the particle type under investigation. Nevertheless, Mie-theory can correctly predict trends. Taking into account several uncertainties in the input parameters for scattering calculations, Mie-theory can be applied in the prediction of scattering and absorption properties in numerical simulations of coal combustion.