Description of the thesis topic

Hydrogen combustion is a promising energy source that will reach carbon neutrality by 2050 in many applications, including transportation, industrial processes, and energy conversion.
This ambitious goal involves significant scientific challenges in terms of combustion since hydrogen's chemical and physical properties are very different from those of conventional hydrocarbon fuels, and high levels of NOx emissions are expected. While the emission and reduction of NOx in turbulent flames have been studied in the case of hydrocarbon combustion, the physical and chemical mechanisms responsible for NOx formation in turbulent hydrogen flames remain unknown. Understanding and modeling NOx formation is essential to develop the numerical tools combustion engineers need to design future hydrogen combustors.
The thesis aims to understand and model NOx formation in turbulent hydrogen flames better through experimental diagnostics focusing on the effect of adding water steam to reduce NOx formation.

The EM2C laboratory is seeking a highly qualified candidate for a PhD fellowship in experimental combustion. The successful candidate will be supervised by Dr. Clément Mirat, Dr. Christopher Betrancourt, and Dr. Laurent Zimmer to study hydrogen combustion diluted with steam. The thesis aims to set up a burner and determine the stability maps of reference flames, particularly in the presence of steam injection. The targeted flames will be turbulent, and global measurements of flame shapes using chemiluminescence will be conducted. At the same time, the gases leaving the combustion chamber will be sampled and inserted into an analysis rack to determine their composition. This first step will help define the experimental configurations to be studied in greater detail in further work. The aim will be to characterize flames with very low NOx emissions and flames that are relatively similar in appearance but have higher emissions.

The second step is to use optical diagnostics to determine flame velocity and flame front position in these reference cases and their impact on NOx output concentrations. To this end, particle image velocimetry (PIV) techniques will be deployed simultaneously with planar laser-induced fluorescence (PLIF) techniques on the OH molecule. Laser-induced phosphorescence (LIP) methods will also determine any correlations between these quantities and wall temperatures. These fundamental results will enable the development of correlations between these different quantities and global emissions.

A PLIF technique on the NO molecule will be applied to a few flames to complete the thesis work. This technique will be used in association with a PIV technique to gain a detailed understanding of NOx production and transport zones in turbulent flames. These fundamental results will enable the development of low-order models of NOx production and transport in hydrogen-air flames in the possible presence of water vapor.

Work Context

The MONTHY project (https://www.pepr-hydrogene.fr/projets/monthy/), involving three academic partners, is part of an ambitious national project to support hydrogen research as part of the national hydrogen plan. The thesis focuses on understanding and modeling the formation of nitrogen oxides in turbulent hydrogen flames to find solutions to their reduction. This fundamental step will enable a rapid transfer to industry via the development of the High-Performance Computing (HPC) tools needed to design tomorrow's hydrogen combustion chambers for a variety of applications: aeronautical propulsion, high-temperature heat production for industry, and land, river, and sea mobility.

The EM2C laboratory (CNRS/INSIS and Université Paris-Saclay/CentraleSupélec http://em2c.centralesupelec.fr/), thanks to its high-level academic research on energy and combustion and its applied studies in partnership with leading transport and energy companies and research centers, is making a significant contribution to the advancement of knowledge on these critical issues, both for the climate and the environment. The laboratory's research activities are organized around three axes: Combustion, Non-equilibrium Plasmas, Transfer Physics, and a transversal action in Applied Mathematics. As a doctoral student (M/F), you will be enrolled in the SMEMAG doctoral school (ED 579 - Mechanical & Energy Sciences, Materials & Geosciences). The EM2C Laboratory has around 45 permanent staff (researchers, teacher-researchers & research support staff) and 35 PhD students, post-docs, trainees & visiting professors.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.