PhD in Mechanical Engineering: Subgrid-scale modeling of thermo-diffusive instabilities in Large Eddy Simulation of turbulent hydrogen combustion

The increasing use of hydrogen (H2) in industry and transport poses problems in terms of the safety of industrial installations. Indeed, H2 is a volatile and flammable molecule which can cause destructive explosions. Computational fluid dynamics (CFD) constitutes an important tool for designing systems and is a complement to experiments, which are expensive and difficult to implement. CFD simulations must nevertheless achieve a high level of fidelity. In the case of the combustion of H2, the numerical models must in particular take into account the effects of thermo-diffusive instabilities, which are a consequence of the very high diffusivity of hydrogen, and which generate a significant acceleration of the flames. These effects are, however, rarely taken into account in CFD models, and are often based on laminar flames, while the interactions between instabilities and turbulence are neglected. The objective of this PhD is to develop a large eddy simulation model taking into account the effects of thermo-diffusive instabilities, as well as their interactions with turbulence. The model will be developed in the formalism of the thickened flame model (TFM), currently used at IFPEN. The thesis will take place according to the following steps: (i) Implementation of direct numerical simulations (DNS), making it possible to understand and acquire detailed data on the interactions between instabilities and turbulence; (ii) development of a model in a TFM context and validation on canonical cases; (iii) test of the model on a practical case of industrial explosion.

Keywords: Hydrogen; Safety; Combustion; Thermo-diffusive instabilities; CFD

Academic supervisor: Dr. Olivier COLIN, IFPEN, ORCID : 0000-0002-8947-3490

Doctoral School: ED579 SMEMAG

IFPEN supervisor: Dr. Cédric MEHL, ORCID : 0000-0003-2293-9281