3 juillet 2025
- Ignition of hydrogen-based fuels : application to safety / Marc Le Boursicaud PhD Defense
Doctorant : Marc LE BOURSICAUD
Date et lieu : le 3 juillet à 14h00 ; amphi N°3 - Centrale Méditerranée, Plot 6, 38 rue Joliot-Curie, 13451 Marseille
Abstract:
Hydrogen safety has long been a critical concern in the aerospace
and nuclear sectors. However, the growing interest in hydrogen as an
alternative fuel for transportation has introduced new safety
challenges. Storage solutions for such applications typically
involve high-pressure gaseous hydrogen tanks operating at pressures of
up to 700 bar. These conditions differ significantly from those
traditionally studied, necessitating the development of predictive tools
to assess ignition risks under these extreme conditions.
This thesis began with the development of a passive scalar approach
to predict hydrogen ignition using computational fluid dynamics (CFD)
tools. This model significantly reduces the numerical stiffness of the
governing equations and, consequently, computational
costs compared to conventional detailed or reduced mechanisms, while
accurately capturing the physical phenomena responsible for ignition,
particularly for high-pressure applications.
The core of this research focused on shock-induced ignition in
cases of high-pressure hydrogen leakage from tanks or pipes. These
scenarios pose numerous challenges, including complex flow dynamics and
strong scale separation between the hydrogen/air diffusion
layer and the flow. Such conditions render direct numerical simulations
(DNS) impractical. To address these challenges, a novel pseudo-1D flow
solver was developed, combining 1D and 3D representations using planar
and spherical coordinates within a unified
formulation. This solver successfully reproduced flow dynamics across
various geometries and pressure ranges and demonstrated applicability to
other pressurized gases. Additionally, the scalar model was applied to
predict ignition within the diffusion layer.
The resulting methodology is particularly efficient in assessing the
ignition risk of high-pressure hydrogen leaks and enables investigations
into geometric effects, including leaks from 2D and 3D tanks or pipes.
This approach was further extended to evaluate the impact of
obstacles placed near the leakage (such as those representative of
engine compartments). The presence of such obstacles induces reflection
of the leading shock wave and its interaction with the
diffusion layer. The methodology was enhanced to account for these
phenomena, revealing that confinement significantly affects ignition
risk for certain geometries and should not be overlooked in safety
analyses.
Finally, the study explored ignition of hydrogen-ammonia blends,
which have garnered interest as alternatives to pure hydrogen.
Analytical expressions were derived to predict ignition times for
canonical cases, and a tailored version of the passive scalar
approach was developed to model these blends effectively.
Jury
Nabiha Chaumeix / Directrice de recherche CNRS, ICARE / Rapporteure
Antonio Sánchez / Professeur, University of California San Diego / Rapporteur
Heinz Pitsch / Professeur, RWTH Aachen University / Examinateur
Josué Melguizo-Gavilanes / Chercheur, Shell ETCA / Examinateur
Arnaud Mura / Directeur de recherche CNRS, Pprime / Examinateur
Bruno Denet / Professeur, Aix-Marseille Université / Président du jury
Pierre Boivin / Chargé de recherche CNRS, M2P2 / Directeur de thèse
Jean-Louis Consalvi / Maître de conférences, Aix-Marseille Université / Co-directeur de thèse
