摘要： Laser-powder-based Directed Energy Deposition (DED) process has been used extensively and becomes more and more popular in part manufacturing, repairing and prototype fabrication. It offers an effective way to deposit material via simultaneous delivery of the powders of desired material and laser beam. Complex physical events take place during the process and have great impacts on the success of the process, in which powder stream and its interaction with laser beam play a crucial role. In this paper, a new comprehensive numerical model for powder stream dynamics and heating process is developed to describe the coaxial powder stream and its interaction with laser beam. Reynolds Averaged Navier-stokes (RANS) approach is used for turbulent continuum gas flow while a discrete phase model (DPM) is applied to describe the dynamic behavior of the powder. Two-way coupling approach is adopted to account for the momentum transfer between gas and powder. A new thermal model is developed for powder stream, in which the interaction between powder stream and Gaussian laser beam is modelled through a novel numerical submodel. The obtained results of powder stream are compared with the experimental results from published literature and show good agreement.