Design of a Cold Spraying nozzle to target the optimal deposition velocity of specific powder materials

A model for designing a Cold Spraying nozzle that ensures optimal acceleration of particles was developed using numerical methods. The model was developed in order to properly expand the gas stream through the divergent part of the nozzle. The optimal acceleration of the particles is assured with a particle mach number of √2 relative to the gas stream. The Method of Characteristics is used in order to develop a geometry for the gas expansion using the Blasius solution in order to calculate the effects of the boundary layer thickness. The model, is capable of developing nozzle geometries of any desired length for the optimal acceleration of a chosen particle size. The Mach number at the nozzle's exit obtained from the model was corroborated through experimentation using a Pitot tube. The model is used to design nozzles that will target critical particle deposition velocities for specific materials and particle size ranges.