Flow separation and liquid rundown in a gas-atomization process

Ünal, A.

doi:10.1007/bf02655918

Cited by 34 publications

(3 citation statements)

References 6 publications

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“…Obviously, the chain shock structure of the gas jet from the outlet of the annular nozzle is less and inconspicuous, which will effectively avoid the rapid attenuation of the jet and benefit the atomization process. [15,22] This is consistent with the gas jet structure of a close-coupled nozzle taken by ünal et al [32] using schlieren technology, which can prove the correctness of the simulation.…”

Section: Analysis Of Dynamic Airflow Fieldsupporting

confidence: 87%

“…Furthermore, the ligaments fall off and break, forming some large droplets of primary atomization. ünal et al [32] used high-speed camera technology to study the primary atomization process of aluminum liquid when the argon atomization pressure is 2.4 MPa. The aluminum liquid forms an annular liquid film structure at the bottom of the delivery tube, and the ligament is broken, which basically verified the principle of the primary atomization in this paper.…”

Section: Primary Atomization Analysismentioning

confidence: 99%

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Impact mechanism of gas temperature in metal powder production via gas atomization*

Wang

et al. 2021

Chinese Phys. B

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This paper aims at studying the influence mechanism of gas temperatures (300 K, 400 K, 500 K, and 600 K) on gas atomization by simulating the integral atomization process of the close-coupled nozzle in vacuum induction gas atomization (VIGA). The primary atomization is simulated by the volume of fluid (VOF) approach, and the second atomization is studied by the discrete phase model (DPM) combined with the instability breakage model. The results show that, at an increased gas temperature, the influences of gas–liquid contact angle and gas temperature in the recirculation zone on the primary atomization are virtually negligible. However, increasing the gas temperature will increase the gas–liquid relative velocity near the recirculation zone and decrease the melt film thickness, which are the main reasons for the reduced mass median diameter (MMD, d 50) of primary atomized droplets. During the secondary atomization, increasing the gas temperature from 300 K to 600 K results in an increase in the droplet dispersion angle, which is beneficial to the formation of spherical metal powder. In addition, increasing the gas temperature, the positive effect of gas–liquid relative velocity increase on droplets refinement overweighs the negative influence of the GMR decrease, resulting in the reduced MMD and diameter distribution interval. From the analysis of the atomization mechanism, the increase in atomization efficiency caused by increasing the temperature of the atomizing gas, including primary atomization and secondary atomization, is mainly due to the increase in the gas drag force difference between the inner and outer sides of the annular liquid film.

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Section: Analysis Of Dynamic Airflow Fieldsupporting

confidence: 87%

Section: Primary Atomization Analysismentioning

confidence: 99%

Impact mechanism of gas temperature in metal powder production via gas atomization*

Wang

et al. 2021

Chinese Phys. B

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show abstract

“…It has been widely applied in research on gas atomisation processes [16][17][18][19]43,44]. Basically, the darkness of Schlieren image represents the gradient of gas density.…”

Section: Model Validationmentioning

confidence: 99%

Modelling compressible gas flow near the nozzle of a gas atomiser using a new unified model

Tong

Browne

2009

Computers & Fluids

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Liquid sheet and film atomization: a comparative experimental study

Hespel¹,

Brunet²,

Dyment³

1995

Experiments in Fluids

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Liquid atomization processes are too complex to allow a purely theoretical study. Therefore experiments are necessary to quantify droplets production. In our problem, the replacement of an original complicated flow by a simpler one, i.e. liquid metal and high gas velocity by water and low air velocity, has led to a relation for the droplet diameter, thanks to dynamical similarity and order of magnitude estimates. Observation of a liquid film disruption development by high speed photography gives some informations about the mechanism of break-up in action. Granulometric measurements by video image analysis have specified the previous dimensionless relation for the mass median diameter. Measurements concern both the film and the sheet atomization; it is shown that the control of the liquid layer thickness is of major importance to control the quality of sprays. List of symbolsd droplet diameter (m) dram mass median droplet diameter (m) g acceleration due to the gravity (m s -2) Hg, H~ gas slit width, liquid film thickness (m) dmma pt pl a2 Nl-5 ', N2 =-ill tt~ pg Vg ' N3= ptQ N4 =ptaHt ' 2 ' Pl P1 p~ Yt N5-dimensionless parameters oQt= Ht Vl PIQI Re=--Pl T vg, v~ Wc we_PgV~H, r Pg, Pl Pg, Pl G liquid flow rate (m2s 1) Reynolds number time(s) gas and liquid velocity (m s-1) channel width (m)Weber number gas and liquid viscosity (kg m l s-1) gas and liquid density (kg m -3) surface tension (kg s-Z)

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Flow separation and liquid rundown in a gas-atomization process

Cited by 34 publications

References 6 publications

Impact mechanism of gas temperature in metal powder production via gas atomization*

Impact mechanism of gas temperature in metal powder production via gas atomization*

Modelling compressible gas flow near the nozzle of a gas atomiser using a new unified model

Liquid sheet and film atomization: a comparative experimental study

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