| This thesis presents a modeling attempt related to low-pressure plasma spraying processes which find increasing applications for materials processing.; After an extensive review of the various models for ionization and recombination processes, a two-temperature model for argon plasmas in chemical (ionization) non- equilibrium is established using finite rate chemistry.; Results of sample calculations for both laminar and turbulent cases manifest departures from the kinetic as well as chemical equilibrium, demonstrating that the conventional models based on the LTE (Local Thermodynamic Equilibrium) assumption cannot provide proper prediction for the low pressure plasma jets.; Contributions of each components of the plasma to the heat and momentum transfer to the particulates injected into plasma flow is studied by simulating plasma flow around a sphere. A model is proposed to study non-equilibrium nature of the boundary layer along with other distinctive characteristics as rarefaction and particle charging effects. Based on this model, a data base is generated to be used for predicting particle trajectories and heating histories. |
