A Study of Liquid Metal Atomization Using Close-Coupled Nozzles, Part 2: Atomization Behavior

Mates, Steven P.; Settles, Gary S.

doi:10.1615/atomizspr.v15.i1.30

Cited by 38 publications

(22 citation statements)

References 11 publications

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“…There is also, perhaps more tentative, evidence for recirculation within the melt plume. Evidence for such recirculation eddies has previously been presented by Mates & Settles (2005) on the basis of Schlieren imaging of the gas only flow. Generally a symmetrical pair of such eddies have been reported although only one is evident here.…”

Section: Resultsmentioning

confidence: 90%

High speed imaging of the flow during close-coupled gas atomisation: Effect of melt delivery nozzle geometry

McCarthy

Mullis

2011

Journal of Materials Processing Technology

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We describe the application of a high-speed still imaging technique to the study of close-coupled gas atomisation. A pulsed Nd:YAG laser is used to obtain pairs of still images with an effective 6 ns exposure time, from which velocity maps of the flow of the atomised fluid can be reconstructed. We demonstrate directly that the melt spray cone consists of a jet precessing around the surface of a cone. Further, we demonstrate that the width of this jet is directly related to the geometry of the melt nozzle. By applying Particle Image Velocimetry techniques we are also able to map the flow field in both the primary and secondary atomisation zones, demonstrating an asymmetric recirculation eddy exists at the circumferential edge of the gas-melt interface in the primary atomisation zone. Keywords: Gas atomisation; Discrete Fourier transform; Particle Image Velocimetry IntroductionClose-coupled gas atomisation (CCGA) is an important production technique for fine, spherical metal powders. Such powders have a variety of uses, such as for pigments, catalysts, metal injection moulding (MIM) feedstock, solder pastes for 'flip-chip' type circuit board fabrication and solid rocket propellant. In principle, CCGA is straightforward: high pressure gas jets impinging upon a molten metal stream are used to disrupt the stream, breaking it up into a series of fine droplets. However, in practice the complex interaction between the high velocity gas jets and the metal results in a turbulent, and often chaotic, flow with the result that the details of the process are far from well understood. Consequently, early work into gas atomisation, such as that by Klov and Schfer (1972) or Bradley (1973), focused on empirical correlations between median particle size and process parameters such as gas pressure, gas flow rate and melt flow rate. The most widely quoted of these empirical relationships is that due Lubanska (1970), which correlates particle size with (1+G)

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Section: Resultsmentioning

confidence: 90%

High speed imaging of the flow during close-coupled gas atomisation: Effect of melt delivery nozzle geometry

McCarthy

Mullis

2011

Journal of Materials Processing Technology

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“…Once reestablished melt is again able to flow into the recirculation zone and the cycle is re-established. However this is disputed by Mates and Settles [8,9] who suggest that wake closure is of no real consequence in atomization as the closed-wake structure is not preserved during the actual atomization process.…”

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confidence: 99%

Log-Normal Melt Pulsation in Close-Coupled Gas Atomization

Mullis

McCarthy

Adkins

2013

Metall Mater Trans B

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High speed photography coupled with sophisticated image analysis has been used to study low frequency pulsation during close-coupled gas atomization. At high gas pressure the instantaneous melt delivery is described by two superimposed log-normal distributions, one with a high standard deviation but little melt at the atomizer tip, the second with low standard deviation but more melt at the atomizer tip. At low gas pressures the distribution is better described by a single log-normal distribution.

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“…Viscoelasticity increases the mean drop diameter and broadens the size distribution. Liquids with atypical properties, such as gels, liquid metal, and strain-thickening liquids, are also studied widely [139][140][141][142][143][144][145][146][147].…”

Section: Complex Fluidsmentioning

confidence: 99%

Breakup Morphology and Mechanisms of Liquid Atomization

Zhao¹,

Liu²

2020

Environmental Impact of Aviation and Sustainable Solutions

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Fuel atomization, the transformation of bulk liquid into sprays, is of importance in jet engines. In this chapter, we will introduce the latest research advances on breakup morphology and mechanism of liquid atomization. On primary atomization, based on the morphological difference, the twin-fluid atomization could be classified into different regimes. The influence of Kelvin-Helmholtz and Rayleigh-Taylor instability on breakup morphology and fragment size is great and nonmonotonic. On secondary atomization, Rayleigh-Taylor instability is considered as the main driving mechanism in different bag-breakup modes; for higher Weber number, it will be in concurrence with the shear instability. Based on ligamentmediated spray formation model, ligament breakup is found to be well represented by the gamma distributions. Atomization of complex fluids has special characteristics and mechanisms. There are also a lot of research advances recently in this field.

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A Study of Liquid Metal Atomization Using Close-Coupled Nozzles, Part 2: Atomization Behavior

Cited by 38 publications

References 11 publications

High speed imaging of the flow during close-coupled gas atomisation: Effect of melt delivery nozzle geometry

High speed imaging of the flow during close-coupled gas atomisation: Effect of melt delivery nozzle geometry

Log-Normal Melt Pulsation in Close-Coupled Gas Atomization

Breakup Morphology and Mechanisms of Liquid Atomization

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