  The vaporization rate of aluminum droplets in shocked flows plays a crucial
role in determining the energy release rate during the combustion of the
aluminized energetic materials. In this paper, the physics of the vaporization
of aluminum droplets in shocked flows is numerically investigated. Surrogate
models for the temporally averaged Sherwood number and Nusselt number, cast as
functions of shock Mach number and Reynolds number, are developed from the
simulation-based data. The results show that the Sherwood number and the
Nusselt number of the droplet increase monotonically with the Reynolds number.
On the other hand, the Sherwood number and the Nusselt number exhibit
non-monotonic behavior with increasing shock Mach number due to the transition
of the post-shock flow from subsonic to the supersonic speeds as the shock Mach
number is increased from 1.1 to 3.5. In contrast with available models in the
literature that are commonly used in process scale computations of aluminum
droplet vaporization, the current models for the Sherwood number and the
Nusselt number are applicable over a wide range of the Reynolds number and the
Mach number and will be useful in the macro-scale multi-phase simulations of
the combustion of aluminumized energetic materials in high-speed flows.
