Numerical simulation and experimental investigation of gas-powder flow from radially symmetrical nozzles in laser-based direct metal deposition

Laser-based direct metal deposition (DMD) is a solid freeform fabrication process capable of fabricating fully dense and metallurgically sound parts. The process has been greatly enhanced toward multi-directional deposition by the use of discontinuous radially symmetrical powder nozzles to supply the build material. Since many operational parameters depend on the gas-powder stream characteristics between the nozzles and the deposition point, an extensive understanding of the gas-powder flow is necessary. Three-dimensional (3D) multi-phase gas-powder flow structures of radially symmetrical nozzles are modeled using computational fluid dynamics methods. The obtained results are in good agreement with the experimental ones, and they provide a good insight into the process phenomena. (C) 2006 Elsevier Ltd. All rights reserved.