Study of ambient turbulence effects on diesel sprays in a fan-stirred vessel

This study investigates the influence of the ambient turbulence on a pressure-atomized diesel-like spray in the well-characterized and controlled turbulence flow field of a fan-stirred experimental vessel. Injections were performed into nitrogen at 15 bar and 400 K under four turbulent conditions, with RMS velocities ranging from 0.5 up to 5.5 m/s. Mie scatter laser sheet and Schlieren techniques were applied to visualize the liquid and the vapor phase of the spray. With increasing turbulence, there was increasing formation of droplet clusters and ligaments, which resulted in a reduced detection of droplet vapor along the whole penetration length of the spray. From considerations of the Stokes numbers fir the droplet-turbulence interaction, it is concluded that the microlength scales of the ambient turbulence were the probable source of this droplet clustering.