抄録
The hot spots that high pressures and temperatures generated during the bubble collapse process, especially in acoustic cavitation, directly related to the physical and chemical reactions. It is very evident that the bubble cloud plays an important role in such reactions and the collapse of bubble clouds under asymmetrical conditions, in particular near a rigid wall or between two walls, is very important. We study the behavior of such bubble clouds in the limited space between solid boundary surfaces for various concentarations C and separation distances S, by means of high-speed motion pictures. The vibratory horn ring was immerged to 5mm of submerged depth in a glass container with an ethanol aqueous solution of 50 cc and drived at resonent frequency of 20 kHz by means of a 700 W amplifier, the corresponding amplitude is 124 μm peak to peak. The bubble cloud observed with time intervals of 1 μs, which is short compared with the 50 μs period of the oscillation by the magnetostrictive driver. The bubble cloud grows and collapses as a single bubble. The maximum diameter of the bubble cloud is relatively large in the range of ,S<0.2mm, for S>1.0mm, the maximum diameter remains a constant. The number of the bubble clouds increases with S in spite of C and the bubble cloud shows nonlinear pulsations in the process.
