Simulation of Near Nozzle Flow Structure of an Effervescent Atomizer

Significant experimental work has been reported in capturing internal and external flow structure involving effervescent atomization in injectors. During effervescent atomization, the flow evolves into various two phase (liquid-gas) structure based on gas-to-liquid ratio (GLR) and injection pressure. The flow that evolves downstream of the discharge orifice has significant effect on the performance of effervescent injector. In the present work, the near- nozzle (external) flow structure of the effervescent injector has been computationally simulated for various internal two-phase flow regimes using Volume of Fluid (VOF) method. In order to avoid geometric complexities and reduce computational cost, only discharge orifice along with external domain was modeled to simulate the external flow. Since the internal flow physics of the effervescent injector was not computed (part of our later study), therefore the different upstream (internal) flow regimes were controlled through User Defined Functions (UDF). The computed results give detailed insight into the near-nozzle external flow structure of effervescent injectors under different gas-to-liquid ratios. This study is the first step towards simulation of complete, internal and external, two-phase flow in effervescent injectors.