2137 超音波領域で生成された微細気泡の径分布測定  [in Japanese] Measurement of Radius Distribution for Micro Bubble Generated in Ultrasonic Field  [in Japanese]

Micro gas bubble generation using ultrasonic wave was investigated experimentally. We found that micro bubbles with around 10μm in average are stably generated from a needle in an ultrasonic field when we supply gas through the needle at several μl/min. In this paper, to clarify the mechanism of the micro bubble generation using ultrasonic wave, we measured the size distribution of the bubbles released from the needle with a microscope. We also investigated the effect of the excited frequency of the ultrasonic wave on the average bubble diameter and the applicability of an analytical expression for a droplet atomization to the fragmentation of the bubble. The results reveal that the average bubble diameter decreases as the excited frequency increases.