SINOPSIS

An alternative use of Rayleigh- and Mie-scattering techniques allows separate examination of high-speed air jets and their airblast atomization characteristics. The molecular clusters of condensed vapor in sonic or supersonic gas jets fall in the Rayleigh range (d<<λ)and the scattered light from these particles can visualize the development of high-speed jets and shear mixing with ambient air. When the tested liquid is injected, the Mie-scattering signals from the spray droplets, which are in the Mie range (d≈λ or d≥λ), enable visualization of the liquid spray development. A comparative study of gas jets and sprays has been made for both converging nozzle (SN type) and a converging-diverging nozzle (CD type). The present visualization study reveals some explanations for the different atomization characteristics of the two types of nozzles under identical injection conditions.