Characterising the cavitation activity generated by an ultrasonic horn at varying tip-vibration amplitudes

Abstract Dual-perspective high-speed imaging and acoustic detection is used to characterise cavitation activity at the tip of a commercial 20 kHz (f0) ultrasonic horn, over 2 s sonications across range input powers available (20 – 100%). Imaging 1 × 105 frames per second (fps) captures cavitation-bubble cluster oscillation horn-tip for duration sonication. Shadowgraphic 2 Mfps, from an orthogonal perspective, probes collapse shock wave generation higher temporal resolution, facilitating direct correlation features within emission data generated by bubble activity. f0/m subharmonic collapses primary directly beneath tip, with m increasing through integer values powers, are studied. Shock waves periodic dominate non-linear emissions noise spectra. Transitional which value indistinct, identified. Overall content signals collected during transitional reduced, relative distinct m. The findings relevant optimisation applications such as sonochemistry, known be mediated phenomena.