Abstract
In order to predict the atomization characteristics of the atomization process of zirconia dry granulation accurately, the influence of nozzle outlet diameter on the atomization characteristics of the atomization process of zirconia dry granulation is analyzed. The VOF method and RNG k-ε turbulence model are applied to numerically analyze the flow field of pressure-swirl nozzles with different outlet diameters of the atomization process of zirconia dry granulation, and the effects of outlet diameters on the spray cone angle, liquid film thickness, pressure distribution and velocity distribution are analyzed. The result shows that when the outlet diameter is increased from 3 to 4 mm, the diameter of air core and the outlet velocity of atomized liquid are increased, the spray cone angle is increased from 30.5° to 59.7° while the liquid film thickness is decreased, but when the outlet diameter is increased to 5 mm, the diameter of air core and the outlet velocity of atomized liquid are decreased, the spray cone angle is decreased to 27.6°, while the thickness of liquid film is decreased. The spray cone angle, moisture content of zirconia particles corresponding to nozzles with different outlet diameters are measured by the design of atomization experiment platform and the microstructure of zirconia particles are observed, which verifies the correctness of numerical analysis. Taking the atomization performance of nozzle into consideration, the pressure-swirl nozzle with the outlet diameter of 4 mm is better suitable for the atomization process of zirconia dry granulation.
Highlights
Atomization is an important part of zirconia dry granulation process, the atomization process is that the atomized droplets sprayed from the nozzle combine with the evenly mixed powder, the size of atomized droplets affect the percentage of powder in the zirconia particles prepared by dry
When the outlet diameter nozzle is less than 4 mm, the discharge of atomized liquid is limited and the gas-liquid twophase mixing time is sufficient in nozzle, so the flow rate of atomized liquid in nozzle plays a leading role in the swirl intensity of gas-liquid two-phase flow in nozzle
When the outlet diameter of nozzle increases from 3 to 4 mm, the flow rate of atomized liquid in nozzle is increased continuously, which makes that the swirl intensity of gas-liquid two-phase flow in nozzle is increased, so the spray cone angle is increased from 28.2° to 58.4°
Summary
The high-pressure area of 2#nozzle mainly distributes on the both sides of swirl chamber, and the central area of swirl chamber mainly forms low-pressure area, which shows that the atomized liquid does not suffer too much friction when it flows at high speed from top to bottom along the wall due to the increase of outlet diameter, it does not cause too much energy loss, but the low-pressure area is distributed along the axis, extending from top to bottom, which can lead to greater pressure difference between the inside and outside of nozzle, so that more gas from outside is sucked into the inside of the nozzle to form air core that accounts for 28% of the total area along the axis.
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