Variation mechanism of aspiration pressure at the tip of metal delivery tube in supersonic atomization

The aspiration pressure variation at the tip of metal delivery tube in the supersonic atomization nozzle during gas-only atomization performance had been investigated in this work. The results reveal that the aspiration pressure is subambient at all operating pressures. A general trend is that with increasing atomization gas pressure, the value of aspiration pressure decreases at P-0 between 0.5 and 1.5MPa, then increases as P-0 ranges from 1.5 similar to 3.5MPa, finally decreases again at higher gas pressure (P-0>similar to 3.5MPa). When P-0>2.0MPa, as the included angle alpha augments, the aspiration pressure Delta P increases. Meanwhile, the change range of aspiration pressure Delta P significantly enlarges when the jet included angle alpha raises from 16 to 28 degrees. The lager is the apex angle beta of metal delivery tube, the greater is the aspiration pressure Delta P. And as the protrusion length of melt delivery tube h increases, the aspiration pressure Delta P decreases gradually.