Cluster collapse in a cylindrical cell: correlating multibubble sonoluminescence, acoustic pressure, and erosion

A cylindrical ultrasonic reactor was driven at eight discrete frequencies in the range 20?150 kHz. Imaging of multibubble sonoluminescence (MBSL) within this cell showed discrete modes of activity throughout this frequency range. This modal activity was compared to the pressure distribution through the cell and also to the erosion/corrosion activity. The erosion/corrosion was detected using an electrochemical method employing a passivated aluminum electrode (250 ?m diameter). Each erosion/corrosion event was counted over a fixed time period (specifically 30 s) and used to map this phenomenon throughout a region of the cell. A strong spatial correlation was shown between the MBSL imaging, the acoustic pressure, and the erosion mapping at relatively low ultrasonic frequencies (here <50 kHz). However, at higher frequencies, although MBSL activity and relatively high acoustic amplitudes were detected, the rate of the erosion/corrosion activity of the system decreased. High-speed imaging (>100000 fps) of a bubble cloud near the electrode surface showed a region of bubble activity, the dynamics of which were correlated to the erosion/corrosion transients produced. These observations contribute to the growing body of knowledge which will allow the development of ultrasonic cleaning systems optimized for particular scenarios.

10.1021/jp1027977

1932-7447

16416-16425

Vian, Christopher J.B.

c5ca4c67-5a34-475e-b99b-04593f9c6cc9

Birkin, Peter R.

ba466560-f27c-418d-89fc-67ea4f81d0a7

Leighton, Timothy G.

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