February 01, 2024
16:30
Louvain-la-Neuve
Place Sainte Barbe, auditorium BARB 91
Interest in the space debris proliferation has been growing substantially over the last decade because of the ever-increasing threat posed by those derelict spacecrafts on the sustainability of future space activities and the risks for on-ground casualties and the environment. A promising technology under development to mitigate this problem consists in designing the spacecrafts in such a way that they can safely re-enter the Earth’s atmosphere at the end of their mission and be destroyed before reaching the ground. The work carried out in this thesis aims to path the way to a numerical framework able to produce simulations with an unprecedented level of fidelity, which is essential to set up the new design for demise paradigm.
This thesis is organized around three main pillars. The first one concerns the modeling of some of the most important phenomena in the aerothermal ablation of melting objects. We lay down general jump conditions at the gas-liquid interface taking into account all the considered phenomena via suitable constitutive laws. We then obtain compressible volume-averaged equations with appropriate closure and equations of state to model the liquid-solid phases with phase transformation.
The models are implemented in the Argo multiphysics platform developed by Cenaero which is based on a discontinuous Galerkin discretization of the conservation laws. The second and central pillar of this thesis is the extension of this available high-order framework to a compressible two-phase sharp interface solver able to preserve its accuracy while resolving the tremendous jumps across the gas-condensed phase interface. We start by improving the accuracy of a level-set method responsible for tracking the interface motion. We then adapt the spatial and temporal schemes such as to obtain an unfitted discretization of the two-phase moving interface problem we are considering.
The last part is about the verification of the implemented models and numerical methods. To do so, we select benchmark test cases assessing several aspects of the solver. We also build up a manufactured solution framework generating reference data satisfying prescribed jump conditions. Finally, we conceive an experimental setup in a cold hypersonic environment which allows us to isolate and observe the ablation mechanisms targeted in this work.
The achievements of this work lay the foundation for extensibility of the framework to models with increasing level of complexity, toward an accurate description of the ablation by melting process.
Jury members :
- Prof. Philippe Chatelain (UCLouvain, Belgium), supervisor
- Prof. Thierry Magin (von Karman Institute)
- Prof. Paul Fisette (UCLouvain, Belgium), chairperson
- Prof. Jean-François Remacle (UCLouvain, Belgium)
- Dr. Pierre Schrooyen (CENAERO, Belgium)
- Prof. Juray De Wilde (UCLouvain, Belgium)
- Dr. Florian Kummer (TU Darmstadt, Germany)
- Prof. Andrea Beck (University of Stuttgart, Germany)