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Accueil du site > Thèmes de recherche > Combustion & systèmes réactifs > 1.1 Détermination des paramètres fondamentaux

1.1 Détermination des paramètres fondamentaux

Fundamental chemical kinetic data are needed to understand and model the combustion processes. Among them, rate constants for elementary reactions and thermochemical properties of chemical species are necessary to propose detailed kinetic reaction mechanisms.

1.1.1 Elementary reactions in combustion
Shock tube studies at ICARE aim at measuring elementary rate constants involving H and O atoms using atomic resonance absorption spectroscopy (ARAS). Several studies concerned the oxidation of hydrogen (PNIR « Carburant et moteurs », action “Hydrogène”, in collaboration with PC2A at Lille), the decomposition of nitrous oxide and its reduction by reaction with hydrogen, and interactions between silane and nitrous oxide (ACL59, ACL65).

1.1.2 Determination of thermo-kinetic parameters
To build chemical kinetic reaction mechanisms, in addition to reaction rate constants, the thermochemical properties of the chemical species involved are needed. Group additivity methods (Benson) have been generally used in the past. Since these methods showed some limitations, ab initio calculations are preferred nowadays. Such methods have been implemented at ICARE to compute accurately the thermochemical properties of a variety of components such as polycyclic hydrocarbons, energetic materials (ACL28, ACL49), biodiesel components and biomass derived chemicals (ACL27, ACL36, ACL50). These studies have been conducted within national research programs (ANR-PNRB GALACSY, and SUPERBIO) and international research contracts (US Air Force).

1.1.3 Chemical kinetic mechanisms
The fundamental parameters determined at ICARE are used to build chemical kinetic reaction mechanisms that in turn are validated against experimental results. The needed experimental databases for model validation are obtained using the techniques listed above. Jet-stirred reactors provide data on the variation of mole fractions of reactants, stable intermediates and products. These data are used together with ignition delays measured in shock tubes, flame speeds, flame structures in premixed flames or opposed flow diffusion flames (through a collaboration with the University of Toronto). Our most recent studies concerned the oxidation kinetics of pure fuels, mixtures, commercial fuels, and surrogates, i.e. natural gas and hydrogen-enriched mixtures (ANR project TACOMA ; programme PIE-CNRS HyTAG), diesel fuel (program PNIR-CAM1 ; CIFRE contracts with IFP), gasoline, E85, bio-fuels, kerosene (contracts CALIN – Pôle de compétitivité Aerospace Valley and FP7 project Alfabird). (ACL4-11, ACL13-17, ACL20-26, ACL29-33, ACL38-40, ACL42-43, ACL44-47, ACL52-58, ACL60-61, ACL64-66, ACL70-72).