Abstract
(1) Conditions for the occurrence of the cavitation were investigated for various values of the external pressure, ultrasonic intensity, frequency, and the size of the bubbles, and the cavitation range was plotted (Fig. 1) (2) By taking into account the variation of the air quantity in bubble accompanying ultrasonic vibration, two kinds of stationary states, namely, stable and unstable ones, can be found theoretically. If the size of the bubble which existed before ultrasonic irradiation is less than the critical value, i. e. the size in unstable stationary state, the vibration of the bubble reaches a stable stationary state. On the other hand, if the size is above the criticla value, it becomes larger and larger. This conclusion may be correlated to ultrasonic degassing from liquid and to the ultrasonic burst of bubble as observed by Willard (1953). (3) In case of stable stationary cavitation, following three graphes were made in nondimensional expressions: (i) the maximum and minimum radii of bubble plotted against ultrasonic intensity (Fig. 4), (ii) the pressure at any distance from bubbble (Fig. 5), (iii) the bubble-radii at any time(Fig. 6).
