Experimental observations of the transition between heterogeneous to homogeneous nucleation regimes in flash-boiling atomization

Abstract

Here we present an experimental study of the transition from heterogeneous to homogeneous-nucleation in flash-boiling atomization. The study is based on a wide set of experimental results obtained with a high-pressure fluid flowing through a simple nozzle. We used the TSI's Phase Doppler Particle Analyzer to measure the spray characteristics; droplets velocity profile, mean velocity, droplets size and droplets size distribution. We conclude that in the heterogeneous-nucleation regime, a higher temperature results in droplets with a lower mean velocity. Upon transition to the homogeneous-nucleation regime at constant pressure, the mean velocity and the size of droplets noticeably increases. Likewise, while in the heterogeneous-nucleation regime, a higher temperature or a higher-pressure results in a lower droplets size (lower SMD), in the homogeneous nucleation regime this trend reverses for both, i.e., a higher temperature or a higher pressure results in a higher droplets size (higher SMD).