Description du sujet de thèse

As part of the development of adaptive materials for space applications, CEA-DAM is studying innovative designs such as ceramic matrix composites. Predicting the behavior of these materials under extremely severe aerodynamic flows requires the study of ablation mechanisms, the production of liquid oxides and their impregnation within the porous network of the composite.
It wasn't until 1988 that the Boltzmann lattice method (LBM) was introduced to overcome these drawbacks. Preliminary studies carried out at the LCTS have shown that the LB method is a genuine alternative to traditional numerical methods.
However, certain avenues of development cannot be ignored. On the one hand, very few studies in the literature have proposed an implicit method applied to LBM, which is essential to reduce computation time, the latter becoming important for three-dimensional studies. However, Asymptotic Preserving AP should be respected to ensure system convergence. On the other hand, studies of the method with unstructured or adaptive meshes are essential in order to take into account the global structure of a composite component with the help of tomography .
For ablative composites, the various components have different thermophysical properties, which have a significant impact on the material's high-temperature response. Macroscopic ablation models address this problem by considering the composite thermal protection material as a whole. At the mesoscopic scale, researchers often focus on the thermomechanical behavior of composites.
There is a need to study material pyrolysis at the thematic scale, and to clarify the mechanism of mesoscopic structural features on the ablation response of the material. What's more, under certain conditions, thermal protection materials may transform into a transient liquid phase, undergoing high pressure and impregnating into a porous medium. These physical phenomena are very difficult to manage on a microscopic scale with traditional codes.

Contexte de travail

LCTS is a joint lab of CNRS, Bordeaux University, CEA and Safran, located on the Bordeaux Campus. It has 35 years experience in basic science research on refractory composites. These high-performance materials are used in aviation, space, energy & industrial applications. LCTS is single research team working in project-oriented mode, in strong relation with its non-academic stakeholders. Currently it includes 34 permanent staff members, plus some 15 PhD candidates and 4 post-doc researchers.

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Contraintes et risques

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