Particle Impaction Patterns from a Circular Jet

Sethi, Virendra; John, Walter

doi:10.1080/02786829308959580

Cited by 44 publications

(32 citation statements)

References 4 publications

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“…6(c) for St = 0.449 (dp = 2 μm) show very similar "donut" shape (having a ring of high particle density toward deposition spot edge) to that found experimentally by Sethi and John (1993) for their case of St = 0.48…”

Section: Tapered Nozzle (With  = 15 O )supporting

confidence: 57%

“…1 (similar to that used by Sethi and John, 1993) are D = 1.5 mm, T/D = 2.0, with various S/D and  .…”

Section: Resultsmentioning

confidence: 99%

“…Both numerical and experimental studies of the gravity effect on particle collection efficiency in inertial impactors were carried out by Huang and Tsai (2001). However, the study of particle deposition patterns with circular laminar jet could only be found in a publication by Sethi and John (1993) with laboratory experiments for one geometric configuration.…”

Section: Introductionmentioning

confidence: 99%

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A Computational Study of Particle Deposition Patterns from a Circular Laminar Jet

Feng

2017

JAFM

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To gain insights into ink material deposition behavior during Aerosol Jet® printing, particle deposition patterns on the plate of inertial impactor with circular laminar jet are investigated numerically with a lagrangian solver implemented within the framework of the OpenFOAM® CFD package. Effects of taper angle of the nozzle channel and jet-to-plate distance are evaluated. The results show quite different particle deposition patterns between tapered nozzle and straight nozzle. At jet Reynolds number Re = 1132, a tapered nozzle deposits particles to form a pattern with a high density ring toward the deposition spot edge, especially when the particle Stokes number St > St50, which is absent with a straight nozzle. Increasing the jet-to-plate distance tends to reduce such particle density peak. Reducing Re to 283 yields particle deposition patterns without the high density ring near the spot edge, with the same tapered nozzle. The particle deposition patterns with the straight nozzle at Re = 283 exhibit further reduced particle density around the spot edge such that the particle density profile appears more like a Gaussian function. In general, the effect of reducing Re on particle deposition pattern seems to be similar to increasing the jet-to-plate distance. The computed particle deposition efficiency η shows the fact that those particles around the jet axis, even with very small values of St, always impact the center of plate, as indicated by the nonvanishing value of η with substantial reduction of St. Such a "small particle contamination" typically amounts to ~10% of small particles (with St < 0.1) at Re ~ 1000 and ~5% at Re ~ 300, which may not be negligible in data analysis with inertial impactor measurement.

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Section: Tapered Nozzle (With  = 15 O )supporting

confidence: 57%

“…1 (similar to that used by Sethi and John, 1993) are D = 1.5 mm, T/D = 2.0, with various S/D and  .…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Computational Study of Particle Deposition Patterns from a Circular Laminar Jet

Feng

2017

JAFM

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“…Analysis of deposits from multiple round nozzle impactor stages (Fang et al 1991), and to a lesser extent even from single round nozzle stages (Sethi and John 1993), shows particle collection in areas other than directly beneath the nozzles where the air jets impinge directly upon the impaction plate. In some cases there are secondary deposits that manifest themselves as "halos" around the primary deposits (both single and multiple nozzle stages), or straight lines directly between adjacent nozzles, both on the impaction plate and on the backside of the nozzle plate (multiple nozzle stages only).…”

Section: Introductionmentioning

confidence: 99%

Study of Secondary Deposits in Multiple Round Nozzle Impactors

Rocklage¹,

Marple

Olson

2013

Aerosol Science and Technology

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Inertial impactors are devices that consist of one or more particle-laden jets impinging onto a surface. Many modern impactors consist of impaction stages that have hundreds of closely spaced jets that, under certain conditions, can influence each other. The objectives of this study were to experimentally quantify the effect of jet interactions on particle collection efficiency, and to determine the underlying collection mechanism. From this testing, three types of secondary deposits were found, defined as midline, nozzle, and halo. The magnitude of these deposits varied widely depending on nozzle spacing, Reynolds number, and particle Stokes number. It was found that midline deposition occurs on a line halfway between adjacent nozzles on the impaction plate, and contains up to 8% of particles entering the nozzle. Midline deposition occurs due to a recirculation zone at the intersection of the two jets. Nozzle plate deposition was found to be minimal, comprising less than 3% of particles entering the nozzle. Nozzle plate deposition occurs due to a secondary recirculation zone created against the backside of the nozzle plate. Halo deposition was found to be the largest source of secondary deposition at low Reynolds numbers with up to 70% of particles entering the nozzle being deposited at this location. These deposits occur due to particle sedimentation. In general, secondary particle depositions cause the collection efficiency curve to be less sharp, with a shift to lower particle Stokes numbers. Application of these results should drive better impactor design with sharper collection efficiency curves.

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“…For example, Lagrangian calculations of particle transport in numericallv simulated laminar flow fields have been successful in several geometries. Experimental studies of impactor collection efficiency curves (e.g., Hering, 1987;Wang and John, 1988;Lee et al, 1990;Marple et al, 1991;Sethi and John, 1993) have been found to be in good agreement with the numerical predictions of Marple and Liu (1974), Rader and Marple (1985), and Jurcik and Wang (1995). The work of Jurcik and Wang (1995) is of particular interest, as they solved for the fluid flow field using the same commercial finite element code (FIDAP) as was used in this work.…”

Section: Introductionmentioning

confidence: 89%

The Virtual Cyclone: A Device for Nonimpact Particle Separation

Torczynski¹,

Rader²

1997

Aerosol Science and Technology

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ABSTRACT. The virtual cyclone, a geometrically uncomplicated device that separates particles from a flow stream by nonimpact particle separation, is discussed. In contradistinction to a cyclone, the particle-laden flow is deflected from its original direction by a wall that curves away from the original flow direction, rather than into it. The computational fluid dynamics code FIDAP (Fluid Dynamics International) is used to perform two-dimensional fluid-flow and particle-motion calculations for a representative device geometry. Flow patterns are found to be insensitive to Reynolds number for values above 100 regardless of whether the flow is laminar or turbulent. Particle-motion calculations for laminar-flow cases indicate that the virtual cyclone geometry examined accomplishes nonimpact particle separation. An approximate analytical relation describing virtual cyclone nonimpact particle separation is developed and found to be in agreement with the numerical simulations. AEROSOL SCILNC'E AND TECHNOL~GY 26:X-573 (1997) O 1997 American Association for Aerosol Research NOMENCLATUREnormalized drag coefficient, 1 for R e , = 0 particle diameter unit normal vector gravitational acceleration (vector) inlet width width in third dimension, normal to plane of calculation particle radial position at inlet radius of curvature at inner edge of inlet radius of curvature at outer edge of inlet, R , = R , + H Reynolds number for fluid, Re = pU(2 H )/IL local Reynolds number for particle, Re,

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Particle Impaction Patterns from a Circular Jet

Cited by 44 publications

References 4 publications

A Computational Study of Particle Deposition Patterns from a Circular Laminar Jet

A Computational Study of Particle Deposition Patterns from a Circular Laminar Jet

Study of Secondary Deposits in Multiple Round Nozzle Impactors

The Virtual Cyclone: A Device for Nonimpact Particle Separation

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