Experimental and modeling study of the ultra-high pressure spray dynamics in the near and far fields under high ambient density conditions

To understand the dynamics of ultra-high pressure injection spray under high ambient density conditions, the spray characteristics in the near and far fields are investigated using long-distance microscope and schlieren, respectively. The effects of nozzle diameter, injection pressure, and ambient density on spray behavior are observed and discussed in terms of spray penetration and angle. Moreover, the 0-D spray models are compared with the experimental data. The results indicate that Zhou's penetration model with a modified parameter shows good agreement with the measured results. The near-field spray dynamics are also analyzed in detail. The injector with a smaller nozzle diameter exhibits longer penetration during the initial stage of injection under all experimental conditions. Taking the nozzle diameter into consideration, an empirical correlation for near-field penetration is developed. Furthermore, the evolution of spray penetration could be divided into two stages due to the trapped effects of residual diesel on fresh diesel. The near-field spray penetration is mainly influenced by the initial in-nozzle fluid state before start of injection and injection parameters, rather than the interaction between the spray and ambient gas.