Powder Flow Simulation of a Ring Type Coaxial Nozzle and Cladding Experiment in Laser Metal Deposition

Abstract

A 3D whole size numerical model of a ring type coaxial nozzle was established to obtain particle space trajectory and convergence character. The realizable k-ε model was applied in the gas flow phase; the powder flow was coupled to the gas flow by Euler-Lagrange approach as a discrete phase model. Different powder material and particle size range were chosen to calculate the powder concentration distribution. The simulated powder stream morphology was in good agreement with the experimental results of high-speed camera observations. Simulating results show that the using of mean diameter \(\stackrel{-}{\text{d}}\) to replace Rossin–Rammler distribution of particle size could also get an accurate flowing characteristic results based on this model, this replacement could save a lot computational resource and shrinkage the computing time. The existing of coaxial shielding gas can impact the powder mass concentration spatial distribution, maximum value convergence height and spot size of the powder flow directly. For 316L with small particle size and Ni60A with large particle size, we found different change regularity and no linear relationship was found. So it was not suggest change the input volume of coaxial shielding gas without special needs. Combining with the laser cladding experiments of Ni60A, results show that the developed ring type coaxial nozzle could transport powder well and prepare excellent deposited layers, the conditional powder utilization ratio can up to 75.9%.