High-speed video microscopy and computer enhanced imagery in the pursuit of bubble dynamics

The equipment and method for studying transient bubble dynamics are described in simple sonochemical reactors and presented using still frames from high-speed video microscopy (500 fps). Effects on aeration bubbles (mean size 1-3 mm diameter) and the cavitation induced species (<0.5 mm diameter) are studied. The images are computer enhanced to improve interpretation of such features as the maximum ellipsoidal distortion at the nodal sound plane and spherical shape regain with due consideration of energy involved and expansion effects at the nodal sound plane. Also immersion depth/pressure effects, as the bubbles transcend the sound field column, in the cylindrical reactor, are recorded for evaluation of nodal and antinodal sound wave effects. Positions of the nodal and antinodal regions are marked using a novel tungsten halogen bulb technique and verified using the sonoelectroluminescent approach with the classical luminol/hydrogen peroxide chemistry which is enhanced under the sound field conditions. (C) 2000 Elsevier Science B.V. All rights reserved.