Complete Breakup of Liquids into Ultrafine Droplets by Grid Turbulence

Ultrafine droplets are crucial in materials processing and nanotechnology, with applications in nanoparticle preparation, water evaporation, nanodrug delivery, nanocoating, among numerous others. While the potential of turbulent gas flow to enhance liquid breakup is acknowledged, constructing turbulence-driven atomizers for ultrafine droplets remains challenging. Herein, we report the innovation of grid-turbulence atomization (GTA), which employs a rotating mesh to deliver liquid and an air knife to spray ultrafine droplets. The airflow across the mesh transitions from laminar flow to grid turbulence, resulting in complete liquid breakup through three stages: bag formation, stretching, and turbulence-induced breakup. Ultrafine water droplets with a 4.8 μm Sauter mean diameter were achieved through GTA. The GTA system demonstrates versatility in atomizing various liquids and proves effective for ultrafine spray-drying. Our strategic methodology establishes a pivotal link between turbulence characteristics and materials processing, influencing a wide range of applications and sparking further innovation in the field.