An atomization model for flash boiling sprays

This paper presents an atomization model for sprays under flash boiling conditions. The atomization is represented by the secondary breakup of a bubble/droplet system, and the breakup is considered as the result of two competing mechanisms: aerodynamic force and bubble growth. The model was applied to predict the atomization of a hollow-cone spray from a pintle injector under flash boiling conditions. In the regimes with intermediate superheat degrees this study considered, sprays are atomized by bubble growth, which produces smaller SMD's than aerodynamic forces alone. With decreasing ambient pressures, the spray cone thickness, fuel vaporization rate and vapor radial penetration increase, but the drop size decreases. With increasing fuel and ambient temperatures sufficiently, the effect of flash boiling and air entrainment completely changes the spray pattern.