Intermediate dynamics of instability evolution in air-blast sprays: from liquid core to ligament to droplets

Abstract This paper presents an extensive study of the air-blast atomization cascade from liquid core to ligaments and droplets. Microscopic backlit images of the sprays were captured along the jet centerline at various axial locations using two orthogonal high-speed cameras. A comprehensive imaging and image processing methodology was performed to enable direct measurements of the wavelength and amplitude of ligament instabilities forming on individual ligaments ejected from the primary liquid jet. This has enabled a complete reconstruction of the link between the probability distribution of the wavelength of ligament instabilities and the subsequent formation of droplets. Statistical analysis revealed the dependence of ligament instabilities on inlet conditions while enabling quantification of the full cascade of processes from the formation of liquid jet as a function of inlet conditions to the subsequent formation of ligaments and then, finally, to droplets.