Effect of evaporation on flow structure of acoustically levitated droplet

摘要

In recent years, the acoustic levitation method has been drawn attention as a promising method for realizing containerless processing. Complicated flow due to the acoustic field occurs an inside and outside of an acoustically levitated droplet. It is also reported that this flow structure is closely related to a phase change behavior such as evaporation of droplets which is essential for a containerless processing. The purpose of this study is to elucidate the internal/external flow structure and the phase change behavior of an acoustically levitated droplet. In order to evaluate the effect of droplet evaporation on the flow structure, visualization of the internal and external flow and the density change of an acoustically levitated droplet with different saturated vapor pressures was performed. The internal flow structure became complicated as the saturated vapor pressure increased. The thickness of the vortices at the end of the droplet decreased as the saturated vapor pressure increased. According to density measurement around droplet by Mach-Zehnder interferometer, the phase difference indicating the density change around the droplet increased as saturated vapor pressure increased.