An experimental study has been carried out to reveal the statistical characteristics of the onset of micro-explosion of an emulsion droplet evaporating and burning on a hot surface. The oil-in-water emulsion consisting of base fuel and water doped with small amount of surfactant is tested after degasification. Detail measurements of the waiting time for the onset of micro-explosion are made for various water contents and surface temperatures. Photographic observation and temperature measurements are made to understand the transport processes of liquid phases inside the droplet and the rate of micro-explosion. The results show that the agglomeration and separation of the water and the base fuel layers occurs prior to the micro-explosion. It is also confirmed that the distribution function of the waiting time is correlated with the Weibull distribution of the wear-out type. An empirical formula is proposed for the rate of micro-explosion as a function of droplet temperature and volume of water layer.
