Development of the Translational Motion Control System for Bubble in Liquid by Acoustic Standing Wave.

It is expected that pure and high performance materials could be manufactured in space under the micro-gravity environment. However, if bubbles are initially trapped in the molten material, they cannot escape from the material under the micro-gravity condition and could adversely affect the product quality. in the present study, an ultrasonic acoustic standing wave field is adopted to control the bubble motion under the micro-gravity environment. At first, the experiment with a single ultrasonic transmitter in a fluid with a free surface was conducted to design and develop new horn. It was experimentally confirmed that the bubble can be held stable and stationary in the ultrasonic wave field with new horn. Next, the bubble control experiment was conducted by using dual ultrasonic vibrators. The ultrasonic acoustic standing wave field was moved by shifting the phase difference between the dual ultrasonic transmitters. It was experimentally confirmed that the present technique is applicable to control the bubble position in liquid. Finally, the experimental results were also confirmed by numerically solving the Rayleigh-Plesset equation and bubble motion equation in the translational direction.