Preliminary Analysis of the Wake Region in Hypersonic Aerobreakup

The aerobreakup of liquid drops along the stagnation streamline of flat-faced, high-speed projectiles (3.03 ≤ M ≤ 5.12) was studied in Dworzanczyk et al. [1]. In that work, the authors provide a database of computational and experimental results. The length and structure of the drop wake region is analyzed in more detail in this paper. Computations were performed with and without viscosity and surface tension; these results show that these parameters don’t change the wake structure significantly. This indicates that the Weber and Reynolds numbers may not be the most meaningful nondimensional numbers in this application. However, the structure of the wake was observed to be strongly dependent on the local Mach number of the flow, in the drop frame of reference. The computational and experimental results show that Mach number has a pronounced effect on two fundamental aspects of the flow: the flow expansion angle around the droplet geometry and the underlying stability characteristics of the shear layer. That is, there is a stabilizing effect of increasing Mach number where the local Mach number is in the 1-2 range.