20.500.12556/RUL-138253 Powder particle–wall collision-based design of the discrete axial nozzle-exit shape in direct laser deposition To improve the efficiency of the direct laser deposition (DLD) of metal powders, a concentrated powder-stream distribution is required, which can be affected by the shape of the powder-delivery nozzle. In this study, a simplified, powder particle–wall collision-based 3D numerical model of the powder flow in the nozzle was used to simulate the influences of the nozzle-exit shape on the concentration of the powder stream distribution, characterized by its diameter. The nozzle-exit shape was parametrized by the exit-cone angle, length, and inner-surface roughness. Based on the simulation results, the nozzle-exit shapes of three exit-cone angles (0°, 3.5° and 7.2°), various lengths and surface-roughness values were designed. For the two larger particle sizes of 22 μm and 82 μm considered, the wall-collision-dominated regime and the influence of the nozzle-exit shape were experimentally confirmed. In particular, a significant decrease in the powder-stream diameter when increasing the divergent nozzle-exit cone angle or decreasing its surface roughness and the nonlinear influence of the cone length were shown. Using single-layer, powder-deposition experiments it was demonstrated that by modifying the design of the nozzle-exit shape, the powder-catchment efficiency was increased by 13% due to the increased nozzle-exit cone angle and by 19% due to the reduced surface roughness. direct laser deposition axial nozzle shapes wall-collision-dominated flow powder-stream distribution powder-catchment efficiency neposredno lasersko nanašanje aksialna oblika šob trčenje sten v prevladujočem toku porazdelitev toka prahu učinkovitost zajemanja prahu true false true Angleški jezik Slovenski jezik Članek v reviji 2022-07-13 09:24:54 2022-07-13 09:24:58 2022-09-15 04:16:28 0000-00-00 00:00:00 2022 0 0 13 str. Vol. 308, art. 117704 Oct. 2022 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 621.7 0924-0136 10.1016/j.jmatprotec.2022.117704 114823683 1-s2.0-S0924013622002163-main.pdf 1-s2.0-S0924013622002163-main.pdf 1 16FDBC1D4C2101A9B1586BF916C64B79 1ffac04da6c7e1e59908fcd8234d12faabef5531a0e12bf4684da2787aadb024 3e1b0174-303a-11ed-92af-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=160687 https://www.sciencedirect.com/science/article/pii/S0924013622002163 1 ab16b041-027c-11ed-8aca-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=158485 Fakulteta za strojništvo 0 0 0