Computations of the Liquid-Phase Penetration in Vaporizing Diesel Sprays Using a Two-Fluid Model: Equilibrium and Non-Equilibrium Effects

A two-fluid model is employed to model vaporizing non-combusting sprays under high injection pressure Diesel conditions. A locally homogeneous flow approximation is considered where the two phases have the same velocity at a given spatial ìocation and time. A non-equilibrium approach to computing droplet vaporization is compared with an equilibrium approach discussed in a previous work. Non-equilibrium effects are included by employing the D2-law for droplet vaporization. The computed liquid penetration is compared with constant volume measurements made under Diesel conditions at the Sandia National Laboratories. The effect of droplet size, injection velocity and ambient density on the liquid penetration is studied. It is shown that non-equilibrium effects are not important when the droplets are relatively small. The process of vaporization is controlled only by turbulent mixing under such conditions. The effect of drop size becomes important when the injected drop sizes are large. Such conditions are likely to occur at low ambient densiiies where the non-equilibrium model predicts better asreement with the measured trends.