Drop Interactions with the Conical Shock Structure Generated by a Mach 4.5 Projectile

Abstract

This work presents measurements of liquid drop deformation and breakup time behind approximately conical shock waves and evaluates the predictive capabilities of low-order models and correlations developed using planar shock experiments. A conical shock was approximated by firing a bullet at Mach 4.5 past a vertical column of water drops with a mean initial diameter of [Formula: see text]. The time-resolved drop position and maximum transverse dimension were characterized using backlit stereo images taken at 500 kHz. The gas density and velocity fields experienced by the drops were estimated using a Reynolds-averaged Navier–Stokes simulation of the bullet. Classical correlations predict drop breakup times and deformation in error by a factor of 3 or more. The Taylor analogy breakup (TAB) model predicts deformed drop diameters that agree within the confidence bounds of the ensemble-averaged experimental values using a dimensionless constant [Formula: see text] compared to the accepted value [Formula: see text]. Results demonstrate existing correlations are inadequate for predicting the drop response to the three-dimensional relaxation of the flowfield downstream of a conical-like shock and suggest the TAB model results represent a path toward improved predictions.

Scale-Resolving Simulation of Shock-Induced Aerobreakup of Water Droplet

“…Finally, the SRS methods adopted here can be also used to estimate the air density and velocity fields actually experienced by the droplet, allowing for more accurate evaluations of classical correlations for breakup times derived from planar shock-drop interactions, for instance, in aerospace engineering research [42].…”