Influence of Nozzle Orifice Shape on the Atomization Process of Si3N4 in a Dry Granulation Process

Abstract

In order to reveal the intrinsic fluid-dynamic mechanisms of a pressure-swirl nozzle used for Si 3 N 4 dry granulation, and effectively predict its external spray characteristics, the dynamics of air-atomized liquid two-phase flow is analyzed using a VOF (Volume of Fraction) method together with the modified realizable k-ε turbulence model. The influence of nozzle orifice shape on velocity distribution, pressure distribution is studied. The results show that the pressure difference in a convergent conical nozzle is the largest with a hollow air core being formed in the nozzle. The corresponding velocity of atomized liquid at nozzle orifice is the largest. Using a self-designed atomization experiment platform, the velocity and pressure of atomized liquid and the spray cone angle are measured for three nozzles with different orifice shapes. The micro-morphology of Si 3 N 4 particles is also determined. These data confirm the correctness of numerical simulation. Considering atomization performance of the nozzle, the contraction conical nozzle is more suitable for the atomization of Si 3 N 4 in practical production based on the dry granulation approach.