Dynamic evolution of low-viscosity fuel particle distribution driven by constant flow

Abstract

The effects of mass concentration and injection pressure on the atomization characteristics of low-viscosity fuel spray are studied in a constant-volume chamber. Microscopic spray parameters are measured by laser diffraction at different axial and radial positions downstream of the nozzle. The results show that the atomization effect is inhibited linearly with the increase of mass concentration. The increase of injection pressure promotes the droplet breakup. However, the trend gradually weakens and becomes more noticeable at high concentrations. Comparing with the concentration, the influence of the injection pressure on the atomization characteristics is dominant. Although low concentration and high injection pressure can promote the droplet breakup, they also increase the probability of droplet collision, resulting in droplet aggregation. This is more evident in low-viscosity fuels. The droplet size increases in the axial direction owing to the aggregation. However, the diameter decreases in the radial direction owing to the outward deflection of small droplets caused by air turbulence and entrainment. In addition, the high-velocity airflow significantly promotes the droplet breakup near the nozzle and spray axis regions and inhibits the aggregation effect. However, the lower-viscosity fuels keep smaller droplet sizes and better atomization in the whole spraying process, which is easier to realize than the higher-viscosity fuels. Overall, low concentration, high injection pressure, and low viscosity of fuel have beneficial effects on the droplet breakup. This is very important for improving the atomization effect of fuel.