Title:
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Multiphase numerical modelling of particle-flow interactions in plasma spraying processes
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The current work looks at the challenges of developing a computational solution for the modelling of the plasma spraying industrial process. A set of three 3D Computational Fluid Dynamics (CFD) models were developed and studied for this purpose. The first model that was implemented looks at the effects the electromagnetic properties have in the properties of the plasma flow in the nozzle of the spraying device. The second model studies the particle in flight atomisation after coding the thermal exchanges in the C++ framework and compares the results with experimental data. The third model studies the particle in-flight atomisation of molten metals and their resulting size distribution. The computational results from the first model agree with contemporary work analysing flows in nozzles of plasma spraying equipment. It also provides quantification of the additional energy exchanges that occur in the nozzle of a plasma spraying device, which are the ones that produce the gradients in velocity and temperature, which are met in plasma spraying processes. Finally, it looks into the effect the presence of dielectric may have on the plasma arc. The second model compares well with experimental data acquired by multiphase flows produced from plasma spraying devices and supports the finding that the Weber number is a good indicator of the deformation patterns of fluid particles, even liquid metal, where the density is much higher than regular liquids. The results of the third model in regards to particle size distribution show agreement with theoretical models of the distribution. The three models can be combined in the order presented, to provide a computational modelling solution which can cover the industrial application of the plasma spraying process, from the nozzle, to finer atomisation, to splat.
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