Missions

In line with the European Green Deal target of reaching carbon neutrality within the aviation industry by 2050, multiple incremental and breakthrough technologies are being researched related to novel aircraft design and propulsion systems. Regarding future propulsion systems, one avenue that is being considered for regional, short and medium-range aircraft types is the use of hydrogen as a fuel source. However, it will require a complete overhaul of aircraft design, refuelling infrastructures, certification processes and aeronautical regulations. As evaluated in the “Hydrogen-powered aviation” commissioned by CleanSky2 in May 2020, H2 propulsion could lead to a climate impact reduction potential between 50 and 75 % in terms of CO2 equivalent compared to the full climate impact of kerosene-powered aviation. Already widely used in the space sector as a fuel used with liquid oxygen, the design and development of hydrogen for civil aircraft remains in its infancy and represents a revolution in the aviation industry. Several critical obstacles must be identified and solved before any serious industrial development can occur. One main issue with H2-air combustion is the production of Nitrogen Oxides (NOx). These NOx are atmospheric pollutants implicated notably in acid rains and ozone pollution.
A European consortium HESTIA (HydrogEn combuSTion In Aero engines) led by SAFRAN was granted a 48-month project to overcome those issues. Among others, the actual NOx emissions have to be adequately quantified and understood to assess the free pollutant emissions of future H2 aircraft combustors.
An initial study led to the development of a method for measuring the concentration of nitrogen oxide molecules in a plane (NO-PLIF). These developments made it possible to obtain temperature and concentration maps in a premixed laminar burner with stoichiometric values ranging from 0.6 to 1.1. The results obtained were compared with results from numerical simulations.
The research proposed as part of this mission is to apply the diagnostic initially developed to situations subject to velocity fluctuations. To do this, the burner flow will be pulsed to create variations in flow rate, resulting in variations in flame surface area. The objective is to obtain quantitative maps of NO concentration and temperature, and to be able to compare them with numerical simulations for different levels of fluctuations.

Activités

You will be responsible for deploying quantitative diagnostics to measure NO concentration in a plane in a pulsed laminar burner in the presence of a hydrogen-air mixture at different mixture fractions. To do this, you will first take measurements by scanning wavelengths to obtain an average temperature map. You will then select an excitation wavelength to determine the local NO concentration. The pulses will be imposed by an electromagnetic vane that you will control using external software, coupled with laser synchronisation to obtain phase-averaged images for different frequencies and pulse amplitudes at the different equivalence ratios studied.
You will also write a report detailing all of these experiments and present the results at European project progress meetings.
Finally, you will participate in training future users of the device to obtain NO concentration maps in different flow configurations.

Compétences

You hold a Master's degree in Research or a degree from an engineering school in fluid mechanics, combustion or energy. You have an appetence for experimentation and data processing and are proficient in laser-induced fluorescence theory.
You have proven experience in the use of laser diagnostics in hydrogen-air flames, particularly for probing the presence of nitrogen oxide molecules in a flow (NO-PLIF).
You possess strong oral and written communication skills, enabling you to effectively present your work orally and write articles for scientific journals.

Contexte de travail

The EM2C Laboratory (CNRS/INSIS and Université Paris-Saclay/CentraleSupélec http://em2c.centralesupelec.fr/), through its high-level academic research in energy and combustion and its applied studies in partnership with the most prominent companies or research centres in the field of transport and energy, contribute significantly to the progress of knowledge on these critical issues, both for the climate and for the environment. To meet these challenges, the laboratory's research activities are organised around three axes entitled Combustion, Out-of-Equilibrium Plasmas, Transfer Physics, and a transversal action in Applied Mathematics. You will be included in the Combustion axe and more precisely in the Aeronautical Propulsion group.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.