Drop properties after secondary breakup

Abstract

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.

Investigation of water droplets, kerosene and ethanol deformation in the air

“…The conducted experiments allowed establishing the real droplet forms, their number, times between forms and other characteristics of typical "strain cycles". The controlling 01038-p. 5 EPJ Web of Conferences influence on the main parameter of typical "strain cycles" in the air for widely used liquids (water, ethanol, kerosene) has been established. Not only the liquid properties (surface-tension, viscosity, density) but sizes, and also droplet motion velocity have this influence.…”

“…It has been identified in experimental and theoretical works [3][4][5][6], that the motion of droplets in gas areas and liquids is the specific sequence of "strain cycles". The "strain cycle" means the time interval t d , when the droplet consistently twice takes the form close to the size, the position of the symmetry axis and other features during its motion.…”

“…It will allow establishing the most typical forms of droplets to use at corresponding processes simulation and transition times from one form to another during movement. It is understandable that, it is necessary to investigate the regularities of deformation not only within the first, but also the group of the subsequent "strain cycles" to extend the possible supplements (for example, perspective gas-and vapor-droplet technologies [9,10]) of received results in contrast to the experiments [3][4][5][6].…”

Features of the Transformation of Small Water Droplets and Large Water Bombs in Free Fall

“…The sequence is characterized by repeating the corresponding forms of droplets. This phenomenon has been demonstrated in works [1][2][3][4][5][6]. The term "deformation cycle" [3] means a time interval t d , when a droplet takes twice consecutively a shape similar to identical (in size, the axis of symmetry and other features) during its motion.…”

Water droplet deformation and breakup in the vicinity of the leading edge of an incoming airfoil

“…Droplet breakup due to strong aerodynamics forces have been widely studied over the last half-century, starting with the works of Lane [56], Hinze [36], Wolfe and Andersen [102], or Ranger and Nicholls [77,78], passing through Krezeczkowski [54], Pilch and Erdman [73], O'Rourke and Amsden [67], Wierzba and Takayama [101], Wierzba [100] or Hsiang and Faeth [40,41] up to the more recent works of Han and Tryggvasson [30,31], Luxford et al [24,60,59], Chen [14], Theofanous et al [92,91], Guildenbecher [29] and Theofanous [90].…”