Modélisation numérique et expérimentale des phénomènes de givrage par accrétion de neige collante

Abstract : The present work aims at studying the atmospheric phenomenon of wet-snow accretion to structures. This phenomenon may induce severe damages to structures. Freezing particles which generate wet-snow accretions are characterized by a mixed phase ice/water. The particle state in this framework is quantified by a dimensionless parameter: the liquid water content defined as the ratio of the particle liquid mass to the whole particle mass. This definition is different form the aeronautical one. In this work, wet snow is produced with an ambient temperature below . Both experimental and numerical approaches are undertaken to investigate the subject. The experimental approach, undertaken in a climatic wind tunnel, is based on the effect on the accretions obtained on a test structure. The particle is tuned by adjusting the ambient temperature of the test chamber. The results are synthesized by a coefficient defined as the ratio of the accretion mass flux to the snow mass flux. A first numerical model assesses the boundary conditions of the accretion model, i.e. the particle size distribution upstream the structure and the associated . The first part of accretion model concerns the study of the particle behavior close to the structure which is quantified with a Stokes number. The efficiency of particles to impact the structure is synthesized by a dimensionless parameter . The analysis of the experimental coefficient according to is developed. This allows to study the efficiency of particles to stick on the structure as a function of the . The result is synthesized by the coefficient. The second part concerns an attempt to model the accretion shape by the sticking efficiency as a function of the particle-surface angle of impact. A series of perspectives are presented.
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Alessandro Vigano. Modélisation numérique et expérimentale des phénomènes de givrage par accrétion de neige collante. Autre. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2012. Français. ⟨NNT : 2012ESMA0026⟩. ⟨tel-00786189⟩

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