Contributions to heat and mass transfer between a plasma jet and droplets in suspension plasma spraying

• We study the post-fragmented droplets of colloidal suspension in a plasma jet.
• The steam mass transfer due to the boiling blocks conductive transfer.
• The plasma relative flow leads to high gradient pressure around the droplet.
• As the capillary pressure is not high enough, the droplet deforms with flow stress.

In suspension plasma spraying, nano-sized particles are injected via a liquid or a solvent into a plasma jet. Due to shear by the plasma jet, the liquid is fragmented into small droplets flying into the gas flow. The present work has focused on a single droplet evaporating into the plasma environment, and considers, on the one hand, the physical analysis of the phenomena and, on the other hand, the characterization of the solvent’s thermal and motion characteristics of evaporation by means of direct numerical simulation of a multiphase flow. Specific parameters such as the evaporation time of the droplet have been estimated. In addition, a validation study has been proposed by comparing numerical simulation and physical analysis. The direct numerical simulation of multiphase flow was based on a compressible 1-fluid model, modified for handling phase change. The employed numerical methods included the volume of fluid (VOF) approach for interface tracking and finite volumes on structured grids.