Transactions of Nanjing University of Aeronautics & Astronautics
Effects of Gas Flow Field on Clogging Phenomenon in Close-Coupled Vortical Loop Slit Gas Atomization
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Abstract:
In order to study the basic characteristics of gas flow field in the atomizing chamber near the nozzle outlet of the vortical loop slit atomizer and its influence mechanism on clogging phenomenon， the computational fluid dynamics （CFD） software Fluent is used to conduct a numerical simulation of the gas flow field in the atomizing chamber near the nozzle outlet of this atomizer under different annular slit widths， different atomization gas pressures and different protrusion lengths of the melt delivery tube. The results show that under atomization gas pressure p = 4.5 MPa， the greater the annular slit width D， the lower the static temperature near the central hole outlet at the front end of the melt delivery tube， and the smaller the aspirating pressure at the front end of the melt delivery tube. These features can effectively prevent the occurrence of the clogging phenomenon of metallic melt. Under an annular slit width of D = 1.2 mm， when the atomization gas pressure satisfies 1 MPa ≤ p ≤ 2 MPa and increases gradually， the aspirating pressure at the front end of the melt delivery tube will decline rapidly. This can prevent the clogging phenomenon of metallic melt. However， when the atomization gas pressure p >2 MPa， the greater the atomization gas pressure， the lower the static temperature near the central hole outlet at the front end of the melt delivery tube， and the greater the aspirating pressure at the front end of the melt delivery tube. Hence， the effect of preventing the solidification-induced clogging phenomenon of metallic melt is restricted. When atomization gas pressure is p = 4.5 MPa and annular slit width is D = 1.2 mm， the greater the protrusion length H of the melt delivery tube， and the smaller the aspirating pressure at its front end. The static temperature near the central hole that can be observed in its front end is approximate to effectively prevent the occurrence of clogging phenomenon of metallic melt. However， because of the small aspirating pressure， the metallic melt flows into the atomizing chamber from the central hole at the front end of the melt delivery tube at an increasing speed and the gas-melt ratio in the mass flow rate is reduced， which is not conducive to the improvement of atomization performance.
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Project Supported:
This work was supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD） and the Simulation and Test of the Flow Field of Gas Atomization Nozzle （No.1001-KFA19184）.
Clc Number:
TF123.2
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