Veröffentlichungen und Präsentationen

In the context of pure oxygen storage and transportation, such as production facilities, spacecraft propulsion systems, and medical oxygen supply, severe accidents still occasionally occur. These incidents, including facility damage, storage tank explosions, and even the complete loss of spacecraft, remain rare but often have catastrophic consequences. They continue to occur despite the use of materials specifically selected and qualified through standardized flammability tests, such as ASTM G124. Consequently, improving the understanding of metallic combustion in oxygen-rich environments remains an important scientific and industrial challenge. In collaboration with industrial partners from the oxygen industry, the present work proposes a numerical approach to investigate the combustion of pure iron and to improve the current understanding of the underlying physical mechanisms. The study focuses on the development of a high-fidelity numerical simulation of the ASTM G124 test, in which a metallic rod is ignited by a laser and its regression rate is experimentally measured. The main challenge lies in the strong coupling between the multiple physical phenomena required to build a predictive model. The combustion of iron in a pure oxygen atmosphere involves the simultaneous interaction of heat transfer, gas-phase flow, liquid iron and molten oxide hydrodynamics, species diffusion, and the formation and detachment of droplets composed of both liquid iron and oxide. A two-dimensional axisymmetric model of a laser-ignited, self-sustained burning iron rod is proposed. A conventional multiphase thermohydrodynamic Eulerian formulation is coupled with two species transport equations describing the diffusion of oxygen and iron, from which the combustion heat release is evaluated. Particular attention is paid to the interaction between the different phases. Two coupled phase-field equations are introduced: the first distinguishes the gas phase from condensed materials (iron and oxide), while the second separates the oxide phase from molten iron. This approach enables the appropriate material properties to be assigned to each phase and provides an accurate localization of the combustion front. Finally, the numerical predictions are compared with experimental observations. Because of the extreme conditions encountered during the ASTM G124 test, direct measurements of local temperature and velocity are not available. The validation therefore relies on comparing the experimentally observed and numerically predicted droplet detachment times. Good agreement is obtained, demonstrating the ability of the proposed model to reproduce the main features of iron combustion under pure oxygen conditions.