Etude du transfert par rayonnement à travers les milieux fibreux

Abstract : This work deals with the study of radiative transfer through participating porous media. The purpose is to produce an experimental and theorical characterization of the behaviour of fibrous insulants. An accurate modelization allows the simulation of radiative transfer starting with the optical and morphological characteristics of the medium. The applied method needs the calculation of spectral directional radiative properties, which are used in the radiative transfer equation, written on a discrete form. The matrix treatment of the problem leads to a rapid solution thanks to the "two-streams" method. We thus obtain the intensity distribution, which we then integrate to calculate the radiative flux. The absence of simplifying hypothesis allows the study of parameters influencing the transfer. Two kinds of applications to real media are presented, in the case of silica fibers and carbon fibers. A collection of results of those materials with the study of the factors influencing them is proposed. The numerical stability of the method is analysed and a comparison with other models is also included. The agreement between the theoretical values of the flux and the experimental results of some other authors shows the accuracy of the modelization. Lastly, an experimental study is presented, allowing the characterization to be completed and another validation of the model to be provided. Bidirectional and directional-hemispherical measures of transmission and reflexion have been carried out thanks to two apparatuses, which are described. The experimental results are analysed, discussed and compared with values given by the model, showing a good agreement between the different methods.
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Pascal Boulet. Etude du transfert par rayonnement à travers les milieux fibreux. Autre. Université Henri Poincaré - Nancy 1, 1992. Français. ⟨NNT : 1992NAN10277⟩. ⟨tel-01754365⟩

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