;The main purpose of this study is to establish a metal-powder recycles system for the Powder Bed Fusion. The recycle system uses pneumatic conveying system for powder recovery. The recycle system decreased metal-powder waste. Overflow powder from the laser sintering machine is recovered and recycled back into the laser sintering machine for reuse. And laser sintering machine can operate for a long time, be more conducive to the development of large-scale production of objects, such as aviation part, equipment, etc. The mechanism of the pneumatic conveying in a curved pipe with different geometric shapes is numerically procedure by using COMSOL Multiphysics in this study. The air flow field and the particle′s motion in the pipe are considered. The gas-solid flow is solved by employing two-way coupled Eulerian-Lagrangian approach. The particle rope, powder deposition and bend erosion due to the collision of metal-powder and wall is also analyzed. Then, design the gas inlet system, the simulation results indicate that improving the design of the gas inlet system will improve the non-uniformity of powder delivery caused by powder deposition.
