Computational analysis of the influence of a substrate, solid shield and gas shroud on the flow field of a plasma jet

Gawne, D. T.; Zhang, T.; Liu, B.

doi:10.1016/s0257-8972(01)01672-3

Cited by 35 publications

(24 citation statements)

References 7 publications

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“…Although a large amount of experimental and modeling results have been reported in the literature (see [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and the references cited therein), our understanding about the thermal plasma jet characteristics, especially about the entrainment of ambient gas into the thermal plasma jet, is still incomplete. When a thermal plasma jet is ejected from a plasma torch and issuing freely into an ambient gas originally at rest (so-called submerged plasma jet), the ambient gas will be entrained (or drawn) into the plasma jet due to the momentum transfer between the jet fluid and the ambient gas, leading to the continuous spreading of jet boundary in radial direction, the increase of the total axial mass flux of the plasma jet and the spatial evolution of plasma temperature, axial velocity and species concentration (if the plasma-forming gas is different from the ambient gas) profiles at the jet cross-sections in the direction of jet axis.…”

Section: Introductionmentioning

confidence: 99%

Modeling Study on the Entrainment of Ambient Air into Subsonic Laminar and Turbulent Argon Plasma Jets

Wang

Chen

Pan

2007

Plasma Chem Plasma Process

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Modeling study is performed to reveal the special features of the entrainment of ambient air into subsonic laminar and turbulent argon plasma jets. Two different types of jet flows are considered, i.e., the argon plasma jet is impinging normally upon a flat substrate located in atmospheric air surroundings or is freely issuing into the ambient air. It is found that the existence of the substrate not only changes the plasma temperature, velocity and species concentration distributions in the near-substrate region, but also significantly enhances the mass flow rate of the ambient air entrained into the jet due to the additional contribution to the gas entrainment of the wall jet formed along the substrate surface. The fraction of the additional entrainment of the wall jet in the total entrained-air flow rate is especially high for the laminar impinging plasma jet and for the case with shorter substrate standoff distances. Similarly to the case of cold-gas free jets, the maximum mass flow-rate of ambient gas entrained into the turbulent impinging or free plasma jet is approximately directly proportional to the mass flow rate at the jet inlet. The maximum mass flow-rate of ambient gas entrained into the laminar impinging plasma jet slightly increases with increasing jet-inlet velocity but decreases with increasing jet-inlet temperature.

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Section: Introductionmentioning

confidence: 99%

Modeling Study on the Entrainment of Ambient Air into Subsonic Laminar and Turbulent Argon Plasma Jets

Wang

Chen

Pan

2007

Plasma Chem Plasma Process

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“…The temperature profiles of polymer coatings during deposition and cooling depend greatly upon the processing conditions and substrate geometry [18,19]. For example, the temperature of the deposit is expected to be increased substantially by increasing the flame power [17].…”

Section: Thermal History During Depositionmentioning

confidence: 99%

“…The flame sweeps across and down the substrate surface depositing one or more layers until the required thickness of coating is built up. The hot gas jet from the spray gun impinges on and flows out laterally over the substrate or underlying layers of coating [17,18]. This imparts significant thermal energy into the coating, which can have a substantial effect on its properties, particularly for polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

Process control for thermal-spray deposition of thermoset coatings using computer simulation

Bao

Gawne

et al. 2016

Progress in Organic Coatings

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Thermal spraying is a green solvent-free process with the potential of applying polymer coatings to large components in-house or on-site without the need for prolonged drying. Almost no systematic research has been undertaken on thermally spraying thermoset coatings owing to the complexity and difficulty of managing the curing process. An adequately cured thermoset coating could not be deposited by thermal spraying owing to insufficient cumulative time above the cure temperature. Preheating and post-heating the substrate under a constant heat source were not successful as they led to non-uniform curing, residual stress and the risk of overheating. This study develops and validates a computer model that simulates the deposition of thermoset coatings on metal substrates using thermal spraying and high-energy infrared irradiation. The model uses readily-available commercial software and enables precise control of the coating process to improve energy efficiency and coating quality. Further research showed that evenly cured coatings could be achieved by using variable heat fluxes and controlled utilization of inward conduction from the outer surface layers. Self curing during cooling was significant and may be employed to increase energy efficiency. The thickness of the metal substrate was shown to be an important variable as it acts as a heat sink and, for heavy sections, can substantially increase energy consumption. The results indicate a need for sufficiently accurate process control and provide a suitable methodology for the deposition of thermoset coatings.

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“…Refs. [3,4] presented some modeling results concerning the effects of the gas shroud and/or solid shield on the characteristics of turbulent plasma jets issuing into air surroundings. They showed that employing the gas shroud and/or solid shield can appreciably affect the temperature, velocity and air concentration fields in the turbulent plasma jets.…”

Section: Introductionmentioning

confidence: 99%

“…Ref. [4] showed that employing a shrouding gas (same as the torch working gas) with a velocity of 100 m/s could reduce the air content from 82% to 46% at the turbulent jet center 105 mm downstream from the torch nozzle exit.…”

Section: Introductionmentioning

confidence: 99%

Modeling study of shrouding gas effects on a laminar argon plasma jet impinging upon a flat substrate in air surroundings

et al. 2006

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With the laminar plasma materials processing as the research background, modeling study is conducted concerning the effects of argon shroud on the characteristics of the laminar argon plasma jet impinging normally upon a flat substrate located in air surroundings. It is shown that adding shrouding gas is an effective method to reduce and control the entrainment of ambient air into the laminar plasma jet. The shrouding gas flow rate or velocity, the injection slot width and the stand-off distance of the substrate appreciably affect the air contents in the plasma near the substrate surface. D

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Computational analysis of the influence of a substrate, solid shield and gas shroud on the flow field of a plasma jet

Cited by 35 publications

References 7 publications

Modeling Study on the Entrainment of Ambient Air into Subsonic Laminar and Turbulent Argon Plasma Jets

Modeling Study on the Entrainment of Ambient Air into Subsonic Laminar and Turbulent Argon Plasma Jets

Process control for thermal-spray deposition of thermoset coatings using computer simulation

Modeling study of shrouding gas effects on a laminar argon plasma jet impinging upon a flat substrate in air surroundings

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