A novel method for the estimation of the acoustic bubble radius distribution

[Display omitted] •An image processing is used to determine the acoustic bubble-radius distribution.•Our method is robust against intensity inhomogeneity and unwanted image objects.•The bubble-radius distribution is obtained for the different ultrasonic conditions. The ultrasonic irradiation of a liquid generates acoustic bubbles. Collapsed bubbles in the acoustic pressure create a hot spot condition consisting of high temperature and pressure. Determining the size of the bubbles is vital in the characterization of the corresponding ultrasound wave and the hot spot condition. In this paper, we estimate the distribution of the radius of acoustic bubbles by an image processing technique based on the Principal Component Analysis. We automatically measure the velocity of the bubbles, calculate their radius, and compare the percentage of small/large bubbles and bubble clusters from their radius distribution. We performed several experiments using ultrasonic horn tips of various diameters and ultrasound powers. The results showed that the mean bubble size for a 3 mm tip is 75.66 µm and 82.36 µm in 5 W and 23 W radiation powers, while for a 20 mm tip, the size is 98.3 µm and 109.06 µm for 80 W and 260 W powers, respectively.