Experimental evidence is presented showing the existence of disruptive burning for two-component fuel droplets and micro-explosive combustion for water-in-single fuel component emulsified drops subjected to high relative velocities ranging from 16 to 19 m/sec. Reynolds numbers, based on the high temperature (1200–1400 K) convective freeslrean conditions and droplet diameter, exceeded 40. Calculations using the one-third averaging rule suggested by other investigators for evaluating the relevant properties lead to Reynolds numbers exceeding 135. The fuels considered in this study were a solution of 50 Vol. % n-hexane-50 Vol. % n-hexadecane and water-in-n-hcxadecane emulsions, with 9 and 18 percent (volume) of water. The substantial decrease in time from ignition-to-disruption (with increased relative gas-droplet velocity) in combination with the observed “droplet-shoulder-oriented disruptions” for the multi-component solution supports the existence of a toroidal vortex-like structure within the liquid phase. Furthermore, the observed micro-explosive behavior of the water-in-n-hexadecane emulsified fuel droplets under highly convective conditions indicates that water and fuel are not vaporizing independently of each other. In addition, the intensity of the micro-explosive event for the emulsified fuels considered does not appear to be inhibited by the high relative gas-droplet velocities.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Energy Engineering and Power Technology
- Fuel Technology
- Physics and Astronomy(all)