Mass diffusion and chemical kinetic data for jet fuel surrogates

The predictive capability of combustion modeling is directly related to the accuracy of the models and data used for molecular transport and chemical kinetics. In this work, we report on improvements in both categories.;The gas kinetic theory (GKT) has been widely used to determine the transport properties of gas-phase molecules because of its simplicity and the lack of experimental data, especially at high temperatures.;The major focus of this thesis is to determine the transport properties of complex molecules and suggest an alternative way to overcome the limitations of GKT, especially for large polyatomic molecules. We also recommend a correction term to the expression of the diffusion coefficients that allows the expansion of the validity of the GKT to include molecules with complex geometries and systems at high temperatures. We compute the diffusion coefficients for three classes of hydrocarbons (linear alkanes, cycloalkanes and aromatic molecules) using Molecular Dynamics (MD) simulations with all-atom potentials to incorporate the effects of molecular configurations. The results are compared with the values obtained using GKT, showing that the latter theory overestimates the diffusion of large polyatomic molecules and the error increases for molecules of significantly non-spherical shape. A detailed analysis of the relative importance of the potentials used for MD simulations and the structures of the molecules highlights the importance of the molecular shape in evaluating accurate diffusion coefficients. We also proposed a correction term for the collision diameter used in GKT, based on the radii of gyration of molecules.;In the field of chemical kinetics, we report on the reaction mechanisms for the decomposition of decalin, one of the main components of jet fuel surrogates. We identify fifteen reaction pathways and determine the reaction rates using ab-initio techniques and transition state theory. The new kinetic mechanism of decalin is used to study the combustion of decalin showing the importance of the new reactions in predicting combustion products.