BREAKUP EVOLUTION AND SPRAY CHARACTERISTICS OF TWIN-FLUID ATOMIZERS WITH VARIOUS GAS-TO-LIQUID RATIOS

This study investigates the jet breakup behavior of twin-fluid atomizers under different gas-to-liquid mass rate ratios (GLRs). Optical visualization experiments were performed to observe the multiphase flow and identify jet breakup patterns. The results indicate that in twin-fluid atomizers, the jet mainly exhibits three different patterns under different GLRs: liquid column, film collapse, and film split patterns. The transitions are influenced by both the GLRs and length of the mixing port. Furthermore, for short and medium atomizers, the dimensionless breakup length initially decreases with increasing GLRs, then slightly increases, and finally decreases again. Therefore, a critical mixing port length exists, beyond which atomization performance does not improve significantly. In addition, the jets emerging from the short and medium atomizers exhibit clear asymmetrical characteristics when the GLRs are within the range of 0.01-0.02. The breakup process on the air supply side is faster than that on the opposite side, resulting in small droplet sizes, high droplet number densities, and great jet velocities on the air supply side. Among the three types of atomizers, the medium atomizer with a length-to-diameter ratio of approximately three presents the broadest distribution of the film split pattern, in which the liquid jet quickly breaks up into ligaments and droplets.