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

A novel high liquid pressure fine spray swirl atomizer has been developed, whichincorporates a spill-return orifice into the rear face of the swirl chamber with the aim of givinga significant reduction in flowrate while maintaining the droplet size. The initial work modifieda commercial atomizer to add spill return. However, drop sizes were considered to be too largeand a new design was constructed based on an earlier work on efficient high-pressure (up to120 bar) swirl atomization. The resulting fine sprays can be used for various applications such ashumidification, cleaning, coating, cooling, and decontamination. The atomizer has been characterizedfor different geometries, supply pressures, and spill-return orifice sizes using a LaserParticle Sizer and Phase Doppler Anemometry. For an exit orifice of 0.3mm diameter and spillorifice 0.5mm diameter, the drop size (Sauter mean diameter) is less than 20μm for flowratesas low as 0.1 litre/min and with a mean axial drop velocity of approximately 12 m/s. An averageliquid volume flux of 0.014 (cm3/s)/cm2 is obtained in the spray at 150mmdownstream