Effect of Delivery Tube Diameter on Melt Breakup and Powder Refinement During Water Atomization of FeSiCr Alloy Powder

Water atomization is widely used for producing FeSiCr alloy powder, in which melt delivery conditions strongly influence jet breakup and powder refinement. In this study, a coupled volume of fluid-discrete phase model (VOF-DPM) was established to investigate the effect of delivery tube diameter (3, 4, 5, and 6 mm) on flow characteristics, interfacial instability, and droplet evolution at a constant water pressure of 120 MPa, and the simulation results were validated by industrial trials. As the tube diameter increased from 3 to 6 mm, the melt mass flow rate rose from 0.100 to 0.368 kg/s, the primary breakup position shifted downstream from 94.6 to 236.5 mm, and the peak negative pressure along the centerline decreased from -41.12 to -31.65 kPa. The simulated average particle size increased from 9.176 to 22.791 μm, while the experimentally measured mean particle size increased from 9.0 to 19.6 μm and the fine-powder yield decreased from 43.77% to 22.28%. Although the 3 mm tube produced the finest powder, it showed a higher tendency for clogging and unstable melt delivery. Overall, the 4 mm delivery tube provided the best balance between powder refinement, size uniformity, and production stability.