Effects of Prefilmer Edge Configuration on Primary Liquid Film Breakup: A Lattice Boltzmann Study

In the current work, lattice Boltzmann (LB) modeling of the primary liquid film breakup for a planar prefilming atomizer is conducted, focusing on the effects of prefilmer edge configuration. To achieve this, a phase-field-based multiple-relaxation-time LB model is developed on body-fitted grids for two-phase flow, which incorporates a wettability treatment scheme. The verification results indicate that the present mathematical method is promising for simulating the primary liquid film breakup near the prefilmer with non-orthogonal edge configurations. Subsequently, the detailed numerical predictions reveal that a prefilmer featuring convergent edge configurations has the potential to improve the primary liquid film breakup significantly. To be more specific, the convergent prefilmer edge restricts the liquid film accumulation, resulting in a reduction in the amount of liquid utilized for feeding ligament growth. Combined with the enhanced shearing effects of airflow in the near wake of convergent prefilmer edges, the ligament breakup length decreases while the ligament breakup frequency increases. It should be noted that the impact of the prefilmer edge configuration on the primary liquid film breakup decreases slightly with an increase in air velocity. Further, the liquid film accumulation and the ligament disintegration follow a similar periodic pattern with pretty consistent frequencies, indicating a coupling relationship between these two stages of the primary liquid film breakup.