Liquid Breakup in Dense Sprays

Abstract

Abstract : Experiments were conducted on deformation and breakup properties of turbulent round liquid jets in uniform gaseous crossflows. Pulsed shadowgraph and holograph observations were obtained for turbulent round liquid jets injected normal to air crossflow in a shock tube. The onset of turbulent primary breakup approached the jet exit, approximating breakup conditions at large Weber numbers. Ligament diameters increased with increasing distance from the jet exit, becoming comparable to the radial integral scale of the liquid turbulence near the end of the liquid column. The correlation between drop Sauter mean diameters and streamwise distance along the liquid jet was not affected by the crossflow, suggesting that turbulent primary breakup dominated aerodynamic effects near the liquid surface. Drop velocities after turbulent primary breakup in croseflow were independent of drop size, with streanwise drop velocities comparable to mean streanwise liquid velocities and cross stream drop velocities somewhat larger than the characteristic velocity of the liquid jet in the cross stream direction. Breakup of the liquid column as a whole approximated the total times of breakup of drops subjected to shock wave disturbances in the shear breakup regime. The mean drop mass flux over the downstream projected area of the liquid column due to turbulent primary breakup at the liquid surface could be correlated by a surface efficiency factor that was small at the onset of breakup but increased to a value near unity as the end of the liquid column was approached.