Numerical modeling of secondary breakup in molten metals gas-atomization using dimensionless analysis

Numerical modeling of secondary breakup in gas atomization of molten metals has been successfully performed by others to optimize the powder particle size distribution for various additive manufacturing techniques and metal alloys. The application of breakup analytical models has been tested and validated through experimental campaigns by several researchers. They have demonstrated the suitability of the models in predicting particle size distribution as a function of process parameters. The limit of these models is a lack of information about the particle shape. Assessing the particle morphology could be of great relevance for optimizing the gas atomization parameters of already produced or new alloys. To overcome this limitation, the method described in this paper resorts to the Volume Of Fluid (VOF) modeling approach. This method does not apply to gas atomization breakup because supersonic velocities bring to unaffordable computation times and lack of metal mass conservation. The new approach is conceived to scale down the high velocity flow towards much lower intensities. It makes use of a reference frame moving with the primary droplet and of the similarity theory. At present, the model has been validated through the comparison with DPM results. It demonstrated to be a reliable alternative model allowing to gain deeper insights. Heat transfer among gas and droplets is not simulated yet, thus the droplet deformation does not stop at the solidification time. Further developments are forecast to allow to freeze the particle shape at the time it is completely solidified. (C) 2020 Elsevier Ltd. All rights reserved.