NUMMERICAL SIMULATION OF THE POWDER DISTRIBUTION IN THE COAXIAL NOZZLE AT THE INTERFAXIAL REGION OF DIRECT LASER METAL FORMING

Abstract

Direct Laser Metal Deposition (DLMD) is a advance technology for forming metal components from metal and super alloys, enabling the creation of intricate geometries
that are difficult to achieve through traditional manufacturing methods. In the process, the distribution of powder flow at the nozzle has a crucial role in determining the
quality of the deposited layer. To study the flow characteristics of the interfacial region, this research used numerical simulation to investigate four coaxial cylindrical
nozzles. The simulation results revealed that the gas flow velocity reached a maximum of 22.1m/s before exiting the nozzle and remained above 20m/s for the following
4mm in the free-flow region from the nozzle orifice. The convergence zone of the four nozzles had a diameter of approximately 3mm, with the highest velocity of around
13m/s. The simulation also revealed the presence of reverse flow into the center of the flow field. Importantly, the powder from the four nozzles converged at the geometric
intersection point of the nozzles, around 11.5mm from the nozzle orifice, with a convergence spot diameter of approximately 2mm maintained over a length of about 6mm.
This enables the relative positioning of the laser and powder convergence zones, facilitating the design and adjustment of the nozzle.