Abstract: The linear stability theory is used to derive a new analytical form of dispersion equation which can be used to describe the diesel cavitation bubble growth stability. The effects of various forces on the temporal stability of cavitation bubble are studied by solving the dispersion equation. The results show that viscous force of the diesel droplet makes cavitation bubble more stable. In addition, compared with the viscosities of air and bubble, the droplet’s viscosity plays a dominant role on the stability of cavitation bubble. The adverse effect of inertial force on the stability of cavitation bubble is the major factor, which has a great relationship with the bubble-droplet radius ratio, and its effect increases rapidly with the increasing of the radius ratio. The compressibility force, the internal aerodynamic force and the surface tension have beneficial effects on the stability of cavitation bubble, and the effect has less relevance to the bubble-droplet radius ratio. The outside aerodynamic force has little impact on the stability of cavitation bubble. At the same time, the breakup of cavitation bubble is studied based on the built breakup criterion, and the result reveals that both the bubble growth speed and the initial bubble-droplet radius ratio have great influence on the breakup of cavitation bubble, there is a maximum breakup radius for a droplet which has certainly initial bubble-droplet radius ratio, and the limited breakup radius gradually decreases with the increasing of initial bubble-droplet radius ratio.

Key words: diesel droplet;supercavitation;cavitation bubble;stability;mathematical model