The distribution of materials in a cloud of fragments at the fragmentation of a drop on a mesh bumper | Mekhanika | kompozitsionnykh | materialov i konstruktsii
> Volume 24 > №3 / 2018 / Pages: 437-460

The distribution of materials in a cloud of fragments at the fragmentation of a drop on a mesh bumper



As it was shown in the previous works the high-velocity perforation of thin steel meshes by aluminum projectile can give rise to cumulative jets generated by the restrained flow of the projectile material through the mesh cells. The intensity and velocity of jets and their spatial distribution depend on the geometry of meshes and on the location of an impact point relatively the symmetry centers of the mesh cell. In this work we estimate the distribution of material among the jets produced as a result of an impact of a falling water drop on a rigid mesh. We consider the process of water drop splitting is similar to the high-velocity case with an aluminum projectile. The hydrodynamic of the interaction of a liquid or plastic projectile with some barrier or surface can be characterized by Weber number. The estimate of these numbers for the case of aluminum projectile and water drop in the range of corresponding velocities reveals the similarity of their values what approve the use of the experiments with a water drop for the modeling of high-velocity experiments with an aluminum projectile. Opposite to the specific features of high-velocity experiments the experiments with falling water drop allow us to study in-situ the process of interest. For the purpose of direct observation we used high-speed photography. The distribution of the material among the jets was estimated by the area of spots left on the sheets of filter paper by the fragment of the drop colored with ink dies. The high-speed photography allowed us to estimate the velocities of the jets that revealed that they had higher velocity than the velocity of the water drop prior to impact – this result is similar to the effect of the acceleration of the jet material observed in the high-velocity experiment with aluminum projectile. Besides we found that the regime of the fragmentation of the water drop lowered the difference among the jet intensities comparatively the regime of quasistatic squeezing of the water drop through the mesh cells. We classified the spatial distribution of jets depending on the distance of the impact points from the centers of symmetry of the mesh cells.