The properties of drop deformation and secondary breakup were observed for shock wave initiated disturbances in air at normal temperature and pressure. Test liquids included water, glycerol solutions, n-heptane, ethyl alcohol and mercury to yield Weber numbers (We) of 0.5-1000, Ohnesorge numbers (Oh) of 0.0006-4, liqnid/gas density ratios of 580-12,000 and Reynolds numbers (Re) of 300-16,000. Measurements included pulsed shadowgraphy and holography to find drop deformation properties prior to breakup, as well as drop size distributions after breakup. Drop deformation and breakup regimes were identified in terms of We and Oh: regimes at low Oh include no deformation, nonoseillatory deformation, oscillatory deformation, bag breakup, multimode breakup and shear breakup as We is increased. However, most of these regimes occur at higher We when Oh values are increased, with no breakup observed for Oh > 4 over the present test range. Unified temporal sealing of deformation and breakup processes was observed in terms of a characteristic breakup time that largely was a function of Oh. Prior to breakup, the drag coefficient evolved from the properties of spheres to those of thin disks as drop deformation progressed. The drop size distribution after breakup satisfied Simmons' universal root normal distribution function for the bag and multimode breakup regimes and could be characterized by the Sauter mean diameter (SMD) alone. Drop sizes after shear breakup, however, did not satisfy this distribution function due to the distorting effect of the core or drop-generating drop. Nevertheless, the SMD after secondary breakup could be correlated in terms of a characteristic liquid boundary layer thickness for all breakup regimes, similar to recent results for nonturbulent primary breakup. Drop properties after secondary breakup suggest that both reduced drop sizes and reduced relative velocities play a role in ending the secondary breakup process.

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An experimental study of drop deformation properties induced by both shock wave and steady disturbances is described. Three test facilities were used, as follows: a shock tube facility for measurements of effects of shock wave disturbances on drops in gases, a IO m high drop tube facility for measurements of effects of steady disturbances on drops in gases, and a 1 m high drop tube facility for measurements of

Drop properties during and after secondary breakup in the bag, multimode and shear breakup regimes were observed for shock-wave-initiated disturbances in air at normal temperature and pressure. Test liquids included water, n-heptane, ethyl alcohol and glycerol mixtures to yield Weber numbers of 15-600, Ohnesorge numbers of 0.0025-0.039, liquid/gas density ratios of 579-985 and Reynolds numbers of 1060-15080. Measurements included pulsed shadowgraphy and double-pulsed holography to find drop sizes and velocities after breakup. Drop size distributions after breakup satisfied Simmons' universal root normal distribution in all three breakup regimes, after removing the core (or drop-forming) drop from the drop population for shear breakup. The size and velocity of the core drop after shear breakup was correlated separately based on the observation that the end of drop stripping corresponded to a constant Ertvrs number. The relative velocities of the drop liquid were significantly reduced during secondary breakup, due both to the large drag coet~cients caused by drop deformation and the reduced relaxation times of smaller drops. These effects were correlated successfully based on a simplified phenomenological theory.

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