Abstract
Purpose of this study is to demonstrate the new application for obtaining the detail information about the secondary atomization processes of a burning emulsion droplet. Secondary atomization was caused by vigorous boiling of superheated water during the fuel droplet burning. The AE (i.e. acoustic emission) measurement, which is commonly used for measuring the fracture processes in the materials, was newly applied to measure the occurrence of bubble phenomena in a burning droplet. n-Hexadecane in water emulsion droplet, which was suspended at the tip of a quartz filament, was burned in a quiescent air environment. The filament was mounted at the center of cylindrical block. AE sensor was mounted on the opposite side of the block. The AE signals of the internal bubble phenomena was successfully measured thorough the quartz filament as an acoustic probe. It is observed that the internal boiling of emulsified water occurs prior to the occurrence of micro-explosion. It is concluded that the distribution function of the waiting time for the onset of micro-explosion and internal boiling are correlated to the Weibull distribution, classified to the wear-out type. It is also concluded that intensity distribution of disruptive events of micro-explosion or internal boiling is successfully evaluated relatively using the AE measurement.
