A way of radically increasing fuel efficiency in diesel engines and improving the ecological characteristics of their operation is the use of water-fuel emulsion. However, in spite of the large number of computational and experimental studies, the physical-chemical mechanism of the effect of the water emulsified in the fuel on the processes of carburation, ignition, and combustion under typical conditions for diesel engines remains unclear, for the most part. In particular, it is assumed that the leading mechanism of water liberation in the fuel and the cause of the additional dispersion of hot water-fuel emulsion droplets is thermal micro-explosions of minute water droplets. In the opinion of many researchers, this effect also explains the mechanical dispersion of the centers of fuel-air jets. Hence emulsification of the fuel leads not only to changes in the kinetics of the ignition and combustion of the mixture, but also affects the pre-ignition stage, the process of carburation. But estimates show that the microexplosion mechanism is possible only at sufficiently low static pressures in the medium, and that micro-explosions occur with large induction times for heating of the water-fuel emulsion droplets such that a large fraction of the fuel has been vaporixed. Therefore the assumption more » that thermal explosions of water droplets are responsible for the evolution of the jet of emulsified fuel is questionable, at least in the initial stages of the process. An alternative model of the evolution of a jet of water-fuel emusion in air has been presented. Emulsification is considered as one of the physical factors that leads to an increase in the dispersion angle of the jet immediately after discharge from the sprayer nozzle. It is known that for high-pressure injection of a liquid into a gas the liquid is stretched over the nozzle cross section and the liquid cavitates. The cavitation breakdown of a liquid under high tension is well known in the physics of shock waves. « less