This thesis deals with the acceleration of chemical kinetics calculations in CFD simulations by relying of machine learning methods. The principle is to replace the resolution of the chemistry in the calculations by an equivalent machine learning model, whose evaluation is much faster than the resolution of the original system of differential equat...
Employés dans les moteurs fusée civiles et militaires, les propergols composites sont caractérisés par une structure hétérogène au niveau microscopique. Ils sont constitués principalement de particules oxydantes insérées au sein d’une matrice de polymère, appelée liant. Le liant maintient l’intégralité structurelle du propergol, et fournit par sa p...
Different laboratory-based and synchrotron-based shock tube techniques were used to study the kinetic mechanisms involved in soot formation from key fuel components and intermediates. In particular, a new high repetition rate shock tube (HRRST) is presented together with its coupling to double imaging photoelectron/photoion coincidence spectroscopy...
The future of combustion processes lies on a significant reduction of pollutant emissions, as well as increased efficiencies. The control of the ignition phase is a critical step towards this goal, in many different configurations. Whatever the application, reproductible initiation of the combustion phase is sought. It is well known that the fuel i...
This thesis presents research work on the construction and development of a new instrument and its utilization in the framework of the CPUF technique (Chirped Pulse in Uniform Flow) to study low-temperature collisional processes of astrochemical interest. The thesis details the characteristics of the CRESUCHIRP apparatus and the technical developme...
Des études en laboratoire à basse température pour explorer des réactions impliquant le radical CN,d’intérêt astrochimique ont été réalisées en utilisant la technique CRESU couplée aux technique de photolyse par laser pulsée - fluorescence induite par laser et spectroscopie micro-ondes à transformée de Fourier à impulsions chirpé. Les coefficients ...
Combustion in Liquid Rocket Engines (LRE) happens in extreme conditions which imply several multi-physics phenomena. For this reason, numerical simulation is used to predict and thus to optimize the engine performances and lifetime. In particular this thesis focuses on two main aspects: turbulent oxy-combustion in diffusion flames of methane at hig...
Combustion of fossil fuels has been used for decades for all kinds of purposes, from generating electricity to make air planes fly but they are also the main source of pollution leading to climate change. New sustainable, less polluting fuels must be studied in order to diminish as much as possible the human impact on the planet. Combustion is a ve...
This thesis focuses on the modeling chemical kinetics for reactions involving pure phases. In the first chapter, a discontinuous ODEs model for reactions with appearance and disappearance of species for any number of minerals is proposed. A regularized version of the model can prove positivity and existence. An explicit analysis in the case contain...
