An experimental investigation of the primary breakup of round nonturbulent liquid jets in gaseous crossflow is described. Pulsed shadowgraph and holograph observations were made to determine the following breakup properties: primary breakup regimes, conditions required for the onset of ligament and drop formation, ligament and drop sizes along the liquid surface, drop velocities after breakup, rates of liquid breakup along the liquid surface, conditions required for the breakup of the liquid column as a whole, and liquid column trajectories. These observations were made for round nonturbulent liquid jets in subsonic crossflow at normal temperature and pressure. The results suggest qualitative similarities between the primary breakup of nonturbulent round liquid jets in gaseous crossflow and the secondary breakup of drops subjected to shock wave disturbances. Phenomenological analyses were effective to help interpret and correlate the new measurements of the primary breakup properties of nonturbulent round liquid jets in gaseous crossflow. Nomenclature C D = drag coefficient C = empirical constant for the shear layer thickness; Eq. (15) C i = empirical constant for the onset of ligament formation; Eq. (4) C pi = empirical constant for the onset of drop formation; Eq. (5) C t = empirical constant for the time of onset of ligament formation; Eq. (11) C xb = empirical constant for the cross stream penetration of the liquid column; Eq. (23) C yb = empirical constant for the time of breakup of the liquid column; Eq. (21) d i = streamwise jet diameter at onset of drop formation d inj = injector passage diameter d j = liquid jet diameter at jet exit d = diameter of ligaments along the liquid jet surface d p = diameter of drops formed by primary breakup L = injector passage length L b = liquid jet breakup length Oh = liquid jet Ohnesorge number, µ Lshear layer thickness ε = surface efficiency factor; Eq. (27) = wavelength of liquid surface waves µ = molecular viscosity ν = kinematic viscosity ρ = density σ = surface tension Subscripts b = location of breakup of entire liquid jet G = gas property i = location of onset of breakup j = jet exit property L = liquid property = ligament property p = property of drops formed by primary breakup ∞ = ambient gas property

An experimental investigation of the deformation and breakup properties of turbulent round liquid jets in uniform gaseous crossflows is described. Pulsed shadowgraph and holograph observations were obtained for turbulent round liquid jets injected normal to air crossflow in a shock tube. Crossflow velocities of the air behind the shock wave relative to the liquid jet were subsonic (36-90 m=s) and the air in this region was at normal temperature and pressure. Liquid injection was done by a pressure feed system through round tubes having inside diameters of 1 and 2 mm and length-to-diameter ratios greater than 100 to provide fully developed turbulent pipe flow at the jet exit. Test conditions were as follows: water and ethyl alcohol as test liquids, crossflow Weber numbers based on gas properties of 0-282, streamwise Weber numbers based on liquid properties of 1400-32,200, liquid/gas density ratios of 683 and 845, and jet exit Reynolds numbers based on liquid properties of 7100-48,200, all at conditions in which direct effects of liquid viscosity were small (Ohnesorge numbers were less than 0.12). Measurements were carried out to determine conditions required for the onset of breakup, ligament and drop sizes along the liquid surface, drop velocities after breakup, liquid column breakup as whole, rates of turbulent primary breakup, and liquid column trajectories. Phenomenological theories proved to be quite successful in interpreting and correlating the measurements.

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An experimental and computational investigation of the primary breakup of nonturbulent and turbulent round liquid jets in gas crossflow is described. Pulsed shadowgraph and holograph observations of jet primary breakup regimes, conditions for the onset of breakup, properties of waves observed along the liquid surface, drop size and velocity properties resulting from breakup and conditions required for the breakup of the liquid column as a whole, were obtained for air crossflows at normal temperature and pressure. The test range included crossflow Weber numbers of 0-2000, liquid/gas momentum ratios of 100-8000, liquid/gas density ratios of 683-1021, Ohnesorge numbers of 0.003-0.12, jet Reynolds numbers of 300-300,000. The results suggest qualitative similarities between the primary breakup of nonturbulent round liquid jets in crossflows and the secondary breakup of drops subjected to shock wave disturbances with relatively little effect of the liquid/gas momentum ratio on breakup properties over the present test range. The breakup of turbulent liquid jets was influenced by a new dimensionless number in terms of liquid/gas momentum ratio and the jet Weber number. Effects of liquid viscosity were small for present observations where Ohnesorge numbers were less than 0.4. Phenomenological analyses were successful for helping to interpret and correlate the measurements.

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