Statistical Analysis of Gas Bubbles Dispersion in Liquid Phase

Water Model Experiment on Bottom Blowing Processes

Abstract

Nitrogen gas was injected into water through a vertical nozzle which was placed at the bottom center of a cylindrical container. Bubbes dispersed in water were detected by electroresistivity probes. Time series data obtained were processed with a micro-computer and subjected to statistical analyses. It was shown that the bubble dispersion was a stochastic process and horizontal distribution of the bubble frequency was represented by a two dimensional Gaussian curve around the jet axis. Cone angle of the bubble dispersion zone was defined explicitly from the locus of threefold standard deviation of the distribution on a vertical plane through the jet axis. The cone angle varied noticeably with the geometry of water vessel which would affect the profile and velocity of the circulating flow in the bulk water. Local rising velocity of bubble was determined by taking cross correlation of two time series data which were obtained from two probes located close each other along the rising path. Size distribution of bubbles was determined locally by a new method which was originated from quantitative stereology. It was shown that the measurement of time series by the electroresistivity probes coupled with the statistical analyses was helpful to investigate the spread and structure of bubble dispersion zone in electrically conductive liquids.