A novel cold spray process flow technique - a numerical investigation

Abstract

The particle deposition rates on the coating surface for three different geometries during the high-pressure cold spray processes were studied and verified in the paper. Analyzes were performed for three different techniques, based on the same de Laval nozzle geometry, but each with a different method of supplying working gas to the system. One case of geometry is called the based case and described the classical flow commonly used in industry. The second case called, the vortex case employs the six attached tubes located at the very beginning of the converging section. The last one, called the combined case, uses classical and vortex cases and is defined as the use of a direct nozzle inlet along with additional tubes for the working gas. For all cases, the spraying process took approximately 0.05 seconds, where the value of the deposition rate was calculated using an internal UDF code algorithm written and implemented in the Ansys FLUENT module. The working fluid was the air combined with the spherical copper particles with a diameter of 20μm. The combined variant achieved the highest value of the accretion rate compared to the other two methods and was 33.6 kgm2. On the contrary, the lowest rate was achieved by the vortex method with a rate of 10.7 kgm2. The distribution of the particles sprayed in this combined method forms a cone; in the basic method, the distribution is uniform and in the vortex method, no repeating structure is formed. It was proven that the combined method also gives the highest accretion rate values.