Microscopic experimental study on acoustic agglomeration of the droplets on wall

Study on the effect of acoustic wave on droplet collision-coalescence process is interesting and helps to better understand acoustic agglomeration mechanism. This study designs and carries out a microscopic experiment to investigate the effect of acoustic wave on wall droplet collision-coalescence process. The derived microscopic images of droplets under the action of different sound waves at different moment are processed and analyzed by binaryzation with iterative threshold, cavity filling, morphological open arithmetic processing, and identification of connected regions, etc. Using a newly defined parameter, equivalent droplet size, the growth rates of the droplets in natural state and under the action of different acoustic parameters are compared and analyzed. The results show that the effect of sound wave greatly accelerates the collision-coalescence process of the droplet, and comparing with sound pressure level (SPL), the frequency of the sound wave is a more effective parameter in promoting the collision-coalescence process of wall droplets, and the lower the acoustic wave frequency results in larger collision-coalescence rate.