Numerical study of the effect of gas-to-liquid ratio on the internal and external flows of effervescent atomizers

Abstract

In an effort to capture the complex evolving interface of internal and external flow in an effervescent atomizer, a compressible Eulerian method, along with the volume-of-fluid method coupled with the large eddy simulation model, are employed in a two-phase flow system. Water is injected into the atomizer with a constant mass flow rate of 0.0133 kg/s (i.e., 800 mL/min). The mass flow rate of air is adjusted to vary the gas-to-liquid ratio (GLR) from 0.55% to 2.6%. It is observed that the increase in the GLR is accompanied by an evolution of the internal flow from a complex bubbly flow to an annular flow, which consequently reduces the liquid film thickness at the discharge orifice. Further studies on the internal pressure illustrate the critical condition, which leads to choked flow and pressure oscillations at the discharge orifice. Increasing the GLR was found to affect the internal flow, resulting in changes to primary atomization parameters such as a shortening of the breakup length and a widening of the spray cone angle. The numerical predictions are in good agreement with the experimental results under the same operating conditions.