The flow focusing nozzle is a new type of nozzle that performs effective atomization of the discrete phase by means of high-speed motion of the continuous phase. The flow pattern and its morphological changes have a significant effect on the atomization

but the influence of different parameters on the morphological change of the flow pattern remains unclear. The flow focusing pattern and morphological changes in the two-phase flow inside the nozzle were simulated numerically

based on the volume of fluid method. The results demonstrate that the ratio of the nozzle-to-capillary distance and capillary diameter

the gas-liquid velocity ratio

and capillary diameter have significant effects on the flow pattern. When the ratio of the nozzle-to-capillary distance H and capillary diameter D increases

or the capillary diameter D increases

the flow pattern tends to transform into a laminar form; however

when the gas-liquid velocity ratio V increases

the flow pattern tends to transform into a turbulence form. Furthermore

we define the cone-shaped expansion rate

cone-shaped focusing rate

and cone angle in order to study the morphological changes in the cone shape inside the nozzle. The results indicate that the morphological change of the cone shape and flow pattern transformation is interrelated. When the cone shape tends to be unstable

the flow pattern changes towards flow blurring

whereas

a stable cone indicates that the flow tends to exhibit a droplet pattern.