This work presents a new technique that enables visualization of the breakup and tracking of the dispersion of a fuel spray in the near-field of the nozzle by means of a phosphorescent tracer. It exclusively visualizes the liquid phase, without interference of the vapor phase. The phosphorescence properties of the dissolved Eu-TTA-TOPO complex are compared for different solutions, including engine-relevant surrogate fuels. A method of internal nozzle excitation is presented, which, when applied to water and heptane-based solutions shows the breakup regime, ligament development, and droplet separation. Laser sheet excitation immediately downstream of the nozzle exit is shown to enable the tracking of dispersion and the determination of the fluid velocity of the tagged fluid volume. The results show an increase in both radial and longitudinal width of the fluid parcels with the distance from the nozzle exit for both the water and heptane solution, depending on the properties of the fluid and its velocity. A variation between the breakup of individual fluid parcels was observed and characterized by tracking dispersion on each breakup sequence. The method is shown to qualitatively measure spray breakup, and to provide unique quantitative information on the dispersion of liquid in sprays.
- Measurement technique