SIMULATION OF COLD SPRAY PROCESS BY FLUENT-6

Abstract

The cold spray process is a modern coating process using high velocity and low process temperature particles for surface modification to improve the surface properties of the substrate, such as adhesion, wettability, corrosion resistance, or wear resistance. Coating may be applied as liquid, gases, or solid. In this process spray particles are accelerated the high velocity by a supersonic gas flow that is generated through only by convergent-divergent (CD) nozzle. Convergent-divergent nozzle could achieve the super-sonic velocity through the divergent section, but there is also some problem if the velocity is greater than the Mach number at the throat then the nozzle would be chocked and no flow of air and particles through the nozzle. In this study, simulation and optimization of the cold spray nozzle and spray process has been done with the help of Modelling software. Cold spray nozzle geometry of (CD) nozzle drawn in GAMBIT and solved by the FLUENT solver. To solved the cold spray nozzle, pressure based solver is used because it is more relevant for the problem, for turbulence model Realizable k-ε flow model has used in this problem because this model is relatively new and differ from the standard k-ε model by two ways firstly it contain a new formulation for turbulence viscosity and secondly it has new transport equation for the dissipation rate. After that providing the operating and boundary condition at the inlet and outlet section of the (CD) nozzle, the discrete phase model is activated. Optimizations of CD nozzle is done at the group injection for the length 10mm, 20mm and 30mm after giving the all parameters and then validate the respective work. The temperature of the particle is highest for the injector length 10mm and lowest for the injector length 30mm. The result also shows that the temperature slightly decreases with increase the length of the injector. This is also found that the optimum result would be getting at the 20 mm length of injection.