A numerical simulation study of the path-resolved breakup behaviors of molten metal in high-pressure gas atomization: With emphasis on the role of shock waves in the gas/molten metal interaction

Kaiser, Rashed; Li, Chengguo; Yang, Sangsun; Lee, Donggeun

doi:10.1016/j.apt.2017.12.003

Cited by 39 publications

(10 citation statements)

References 21 publications

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“…Another apparent observation from Figure 6 was that, at lower u g /u l , by increasing relative velocity, the SMD decreased erratically, while this trend reached a plateau state at higher values of u g /u l . This trend has been explained by the creation of shock cell patterns once air flow is choked at higher Mach numbers [38,39]. These shock waves which were absent at lower relative velocities started forming at higher Mach numbers (0.5) and dampened the rate of SMD decrement.…”

Section: Data Comparisonmentioning

confidence: 95%

Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Poozesh

Akafuah

Campbell

et al. 2020

Fluids

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Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form of the conservation equations to create a system of equations by solving which, the far-field secondary atomization can be analyzed through predicting droplet size and velocity distributions of the involved phases. To validate the model predictions, experiments are conducted at ambient conditions using water, methanol, and acetone as model fluids with varying formulation properties, such as density, viscosity, and surface tension. Droplet size distribution and velocity are measured with laser diffraction and a high-speed camera, respectively. Finally, an attempt is made to utilize non-scaled parameters to characterize the atomization process, useful for extrapolating the sensitivity analysis to other scales. The merit of this model lies in its simplicity for use in process control and optimization.

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Section: Data Comparisonmentioning

confidence: 95%

Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Poozesh

Akafuah

Campbell

et al. 2020

Fluids

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“…This equation can be used in gas atomization analytical models for convergent-divergent nozzles, and its results were considered as a reference to estimate the gas velocity at the outlet point of the nozzle 35 . It is known that the gas velocity is also a function of the position considering the atomization nozzle as a reference 29,36,37 , but this is not taken into account in Equation 5. Thus, this equation should be considered an estimative for atomization gas velocity and, therefore, it is a limitation of this model.…”

Section: Mathematical Modelmentioning

confidence: 99%

Evaluation of a Mathematical Model Based on Lubanska Equation to Predict Particle Size for Close-Coupled Gas Atomization of 316L Stainless Steel

2022

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Close-Coupled Gas Atomization (CCGA) is often used to produce spherical metal powders with a wider Particle Size Distribution (PSD) (10 -500 µm) compared to that required by the main Additive Manufacturing processes (10 -105 µm). This work presents an accuracy evaluation of a mathematical model based on the Lubanska equation to predict the d50 for CCGA. Atomization experiments of 316L steel were conducted to evaluate the tip diameter and atomization gas pressure effects on PSD and, the d50 experimental results were used as the reference to the mathematical model evaluation. The mathematical model accuracy could be improved by: (i) considering the backpressure phenomenon for the metal flow rate calculation, since it was an important inaccuracy source; (ii) reviewing the tip diameter effect, which had a lower impact on d50 than that predicted by the Lubanska equation. The atomization gas pressure was the most influential parameter on d50 and d90 and the increase of the gas pressure led to a significant reduction in PSD and, consequently, increased yield.

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“…[43][44][45] The existence of gas shock wave structure can accelerate the attenuation of gas, which is not conducive to the efficient preparation of fine powder. [17,25] Further, limited by the nozzle structure, the gas jet gathers at a certain angle to the center of the nozzle bottom. During this process, the flow path of airflow gradually deflects and forms a recirculation structure [46] above the intersection of the airflow.…”

Section: Close-coupled Nozzle Gas-liquid Flow Velocity Field Analysismentioning

confidence: 99%

“…Thompson et al [24] demonstrated that the Kelvin-Helmholtz Rayleigh-transport (KH-RT) break-up model could be utilized to predict the particle size distribution of close-coupled nozzles. Kaiser et al [25] employed the KH instability break-up model to simulate the interaction between gas shock wave and metallic melt. The results revealed that the shock wave structure is unfavorable for the refined powder.…”

Section: Introductionmentioning

confidence: 99%

Close-coupled nozzle atomization integral simulation and powder preparation using vacuum induction gas atomization technology*

Wang¹,

Li²,

Wang³

et al. 2021

Chinese Phys. B

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We simulate the gas-atomization process of a close-coupled annular nozzle for vacuum induction gas atomization at a three-dimensional scale. Moreover, the relationship between the simulated droplet type and experimentally metallic powder is established by comparing the morphology of droplets with powders. Herein, the primary atomization process is described by the volume-of-fluid (VOF) approach, whereas the prediction of powder diameter after secondary atomization is realized by the VOF-Lagrangian method. In addition, to completely reflect the breaking and deformation process of the metallic flow, we employ the VOF model to simulate the secondary atomization process of a single ellipsoidal droplet. The results show that the primary atomization process includes the formation of surface liquid film, appearance of serrated ligaments, and shredding of ligaments. Further, gas recirculation zone plays an important role in formation of the umbrella-shaped liquid film. The secondary atomization process is divided into droplet convergence and dispersion stages, and the predicted powder diameter is basically consistent with the experiment. In general, the four main powder shapes are formed by the interaction of five different typical droplets.

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A numerical simulation study of the path-resolved breakup behaviors of molten metal in high-pressure gas atomization: With emphasis on the role of shock waves in the gas/molten metal interaction

Cited by 39 publications

References 21 publications

Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Evaluation of a Mathematical Model Based on Lubanska Equation to Predict Particle Size for Close-Coupled Gas Atomization of 316L Stainless Steel

Close-coupled nozzle atomization integral simulation and powder preparation using vacuum induction gas atomization technology*

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