A new fine spray, low flowrate, spill-return swirl atomizer

Abstract: A novel high liquid pressure fine spray swirl atomizer has been developed, which incorporates a spill-return orifice into the rear face of the swirl chamber with the aim of giving a significant reduction in flowrate while maintaining the droplet size. The initial work modified a commercial atomizer to add spill return. However, drop sizes were considered to be too large and a new design was constructed based on an earlier work on efficient high-pressure (up to 120 bar) swirl atomization. The resulting fine sprays can be used for various applications such as humidification, cleaning, coating, cooling, and decontamination. The atomizer has been char-acterized for different geometries, supply pressures, and spill-return orifice sizes using a Laser Particle Sizer and Phase Doppler Anemometry. For an exit orifice of 0.3 mm diameter and spill orifice 0.5 mm diameter, the drop size (Sauter mean diameter) is less than 20μm for flowrates as low as 0.1 litre/min and with a mean axial drop velocity of approximately 12 m/s. An average liquid volume flux of 0.014 (cm3/s)/cm2 is obtained in the spray at 150 mm downstream