Investigation of the Secondary Atomization in Prefilming Air-Blast Atomizers

This study concentrates on the behavior of dispersed droplets after the breakup process and droplet size spatial development from air blast atomizers which use the kinetic energy of co-flowing high-velocity air. Two atomizers having different geometries were utilized to perform high-resolution local velocity and droplet size measurements using phase Doppler Anemometry (PDA). The correlation between all captured droplet sizes and droplets axial velocity at four different locations in a spray was explained. After examination several distribution functions, the log-normal distribution has been found to be well fitting in the current experimental data of droplet diameters along the spray center line. The evaluation of D0.1, D0.5, D0.9 and relative span factor along the spray axial direction have been determined to explain the phenomena occurring in far field of a spray. Finally, it was observed that the effect of a small tolerance of the liquid exit tube in axial direction which may occur during manufacturing will significantly reduce the spray performance.