Cavitation Nuclei Measurements With an Optical System

Many recent experiments have shown the significance of cavitation nuclei, i.e., gas bubbles and/or particulate; however, progress in making quantitative predictions of cavitation depends upon some knowledge of cavitation nuclei properties such as shape, size distribution and concentration. Thus, research has also been concerned with developing measuring systems that give the statistics of the cavitation nuclei distribution. There are many different systems currently being developed; however, only the accuracy and application of the light-scattering technique initially developed by Keller is addressed in this paper. A model is formulated based on appropriate statistical analysis that defines the accuracy for a given sample size. Very good agreement has been found between microbubble distributions measured with the light-scattering system and with holography. Microbubble distribution data were obtained in the 305 mm water tunnel for different air content levels, tunnel static pressures and several tunnel velocities. These data are compared to nuclei distributions obtained at other facilities.