Mechanism of atomization of a liquid jet

TLDR

In the atomization regime of a round liquid jet, a diverging spray appears immediately at the nozzle exit, yet the controlling mechanism remains undetermined despite several proposed theories. The study aims to identify the specific process by which nozzle geometry influences atomization in a liquid jet. Experiments varied liquid pressure, gas type, and nozzle geometry, using fourteen nozzles with length‑to‑diameter ratios from 0.5 to 85 and exit diameters of about 340 µm, to probe atomization behavior. None of the existing theories—whether aerodynamic, turbulent, velocity‑profile, or pressure‑oscillation based—sufficiently explain the observed atomization, indicating that a combined liquid–gas aerodynamic interaction with nozzle geometry is required.

Abstract

In the atomization regime of a round liquid jet, a diverging spray is observed immediately at the nozzle exit. The mechanism that controls atomization has not yet been determined even though several have been proposed. Experiments are reported with constant liquid pressures from 500 psia (33 atm) to 2500 psia (166 atm) with five different mixtures of water and glycerol into nitrogen, helium, and xenon with gas pressures up to 600 psia (40 atm) at room temperature. Fourteen nozzles were used with length-to-diameter ratios ranging from 85 to 0.5 with sharp and rounded inlets, each with an exit diameter of about 340 μm. An evaluation of proposed jet atomization theories shows that aerodynamic effects, liquid turbulence, jet velocity profile rearrangement effects, and liquid supply pressure oscillations each cannot alone explain the experimental results. However, a mechanism that combines liquid–gas aerodynamic interaction with nozzle geometry effects would be compatible with our measurements but the specific process by which the nozzle geometry influences atomization remains to be identified.