Study on Acoustic Cavitations in the Ultrasonic Radiation Field

Applications of ultrasound in cleaning industry and biomedical field are owed to acoustic cavitations. To investigate behaviors of acoustic cavitations, a standing wave field of piston ultrasonic radiation was set up in this paper. And the behaviors of acoustic bubbles in this standing wave field were studied experimentally. Expressions of sound pressure in this standing wave field with di ff erent boundary conditions were discussed. Drawn by the forces (Bejerknes forces, Buoyancy forces, etc.), stable bubbles distributed regularly in the standing wave field. Experiments were conducted to validate that the distribution of stable bubbles can visualize the distribution of sound pressure. Erosion tests on aluminum foiling demonstrate that erosion only occurs in sound pressure anti-node field which was caused by collapsed acoustic bubbles. The radial oscillation of acoustic bubble was observed using high speed camera; it was found that the bubble’s radius was increased with increase of negative sound pressure.