Some functional aspects of air-jet nebulizers

Niven, Ralph W.; Brain, Joseph D.

doi:10.1016/0378-5173(94)90338-7

Cited by 47 publications

(31 citation statements)

References 16 publications

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“…There must be a dynamic balance between the liquid aspiration rate and the liquid removal rate in the jet expansion channel, for a sustainable continuous atomization. Data from rigorous measurements [4] indeed show an increase followed by a decrease in the liquid aspiration rate (in units of ml/min) with increasing air pressure P g (or gas flow rate Q) for several "air-jet" nebulizers, while all nebulizers tested show declining trends of liquid aspiration rate in units of "ml per liter of air" with increasing air flow rate (for Q > 2 L/min).…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, most inks used in the Aerosol Jet® pneumatic atomizer usually have viscosity  ink > 100 cp (and some may even reach 1000 cp), more than two orders of magnitude greater than that of water and dilute aqueous solutions used by May [1], Niven and Brain [4]. For a comparable aspiration rate, syphoning the Aerosol Jet® inks would require a P > 18000 Pa on top of the hydrostatic pressure (about 400 Pa), which does not seem possible with a gas flow rate Q < 2000 sccm (in view of Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…However, the gas flow rate used with the Collison nebulizer was typically Q > 2000 sccm [1] (likely to be with ~2400 sccm at P g = 20 psig according to the measurements of Niven and Brain [4]), which is expected to produce much more negative pressure (e.g., P > 3000 Pa in view of Table I) than needed for just water aspiration. Hence, the syphoning rate of water is likely restricted by the amount of water accumulated in the jet expansion channel due to limited water removal rate by the blowing gas stream.…”

Section: Resultsmentioning

confidence: 99%

“…At the minimum gas flow rate (e.g., Q = 600 sccm or so) for atomization, the magnitude of negative pressure P may only reach the threshold to bring liquid ink up to the jet expansion channel, with little extra for sustaining the expected liquid aspiration rate in the syphon tube (e.g., > 10 ml/min, as typically measured with various "air-jet" nebulizers [4], corresponding to > 10 cm/s average liquid flow velocity in a syphon tube of 1.5 mm diameter). But as the liquid accumulates in the channel, the channel diameter shrinks and the magnitude of negative pressure increases, leading to greater liquid aspiration rate until a dynamic balance in the liquid holdup is established with the liquid removal rate.…”

Section: Resultsmentioning

confidence: 99%

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A Computational Analysis of Gas Jet Flow Effects on Liquid Aspiration in the Collison Nebulizer

Feng¹

2018

Proceedings of the 5th International Conference of Fluid Flow, Heat and Mass Transfer (FFHMT'18)

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-Pneumatic nebulizers (as variations based on the Collison nebulizer) have been widely used for producing fine aerosol droplets from a liquid material. The basic working principle of those nebulizers has been qualitatively described as utilization of the negative pressure associated with an expanding gas jet to syphon liquid into the jet stream, then to blow and shear into liquid sheets, filaments, and eventually droplets. Detailed quantitative analysis based on fluid mechanics theory is desirable, to gain in-depth understanding of the liquid aspiration mechanism among other aspects of the Collison nebulizer behaviour. The purpose of present work is to investigate the nature of negative pressure distribution associated with compressible gas jet flow in the Collison nebulizer by a computational fluid dynamics (CFD) analysis, using an OpenFOAM® compressible flow solver. The value of the negative pressure associated with a gas jet flow is examined by varying geometric parameters of the jet expansion channel adjacent to the outlet of jet orifice. Such an analysis can provide valuable insights into fundamental mechanisms for liquid aspiration, helpful for designing improved pneumatic atomizer in the Aerosol Jet® direct-write system for micro-feature, high-aspect-ratio material deposition.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

A Computational Analysis of Gas Jet Flow Effects on Liquid Aspiration in the Collison Nebulizer

Feng¹

2018

Proceedings of the 5th International Conference of Fluid Flow, Heat and Mass Transfer (FFHMT'18)

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“…later publications [4,5] offering more data regarding some functional aspects of various pneumatic, or air-jet, nebulizers, the discussion of basic working principle remained at the level of qualitative hand-waiving.…”

Section: Introductionmentioning

confidence: 99%

A Computational Analysis of Gas Jet Flow Effects on Liquid Aspiration in the Collison Nebulizer

Feng¹

2018

Preprint

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Abstract-Pneumatic nebulizers (as variations based on theCollison nebulizer) have been widely used for producing fine aerosol droplets from a liquid material. The basic working principle of those nebulizers has been qualitatively described as utilization of the negative pressure associated with an expanding gas jet to syphon liquid into the jet stream, then to blow and shear into liquid sheets, filaments, and eventually droplets. Detailed quantitative analysis based on fluid mechanics theory is desirable, to gain in-depth understanding of the liquid aspiration mechanism among other aspects of the Collison nebulizer behavior. The purpose of present work is to investigate the nature of negative pressure distribution associated with compressible gas jet flow in the Collison nebulizer by a computational fluid dynamics (CFD) analysis, using an OpenFOAM® compressible flow solver. The value of the negative pressure associated with a gas jet flow is examined by varying geometric parameters of the jet expansion channel adjacent to the outlet of jet orifice. Such an analysis can provide valuable insights into fundamental mechanisms in liquid aspiration process, helpful for effective design of improved pneumatic atomizer in the Aerosol Jet® direct-write system for micro-feature, high-aspect-ratio material deposition in additive manufacturing.

show abstract