Combustion of emulsion-based foam

Results of the experimental and theoretical investigations of flame propagation in foams based on hydrocarbon-in-water emulsions are presented. Experimental data refer to the combustion of foams consisting of oxygen bubbles with diameters within 70–130 microns distributed in o-xylene-in-water and cyclohexane-in-water emulsions. Flame propagation velocities were determined for the combustion of various foams in semi-open ended tubes and a foam layer in the atmosphere, and it was established that oscillating regimes of flame propagation in these systems were possible. A decrease in the content of fuel in the initial emulsion leads to decrease in the amplitude of pulsations in the velocity of flame propagation. Estimates of the flame front propagation velocity (flame speed) in foams were obtained and the limits of flame propagation were established. A qualitative analytical model is proposed that describes the experimentally observed phenomenon of flame speed oscillations.