Analysis of Two-Phase Flow in an Effervescent Atomizer Using Volume of Fluid Method

Effervescent atomizers have an edge over conventional single and twin fluid atomizers in terms of smaller ejected drop size. The flow structure upstream of the discharge orifice is one of the major contributory factors towards better performance. In past, many experimental studies have been done to analyze the flow structure produced inside the atomizer and its effect on the resulting spray structure. Few numerical studies were also carried out to simulate and validate the experimental work carried out in this domain. These numerical studies have used various strategies for computing two-phase flows but the use of Volume-of-Fluid (VOF) method has somehow been limited. The present paper not only validates the use of VOF technique for simulating realistic effervescent atomization but also captures details of the internal two phase flow. The flow structure observed during the simulations at various gas-to-liquid mass flow ratios (GLR) was compared with the numerical results and empirical correlation of experimental data available in literature. The results were found in close agreement to previous published results. In addition to the effect of GLR on characteristic liquid film thickness in discharge orifice, effect of geometric profile and gas-liquid interaction was also evaluated at different GLRs. This gives a better insight into the characteristics of internal two phase flow structure.