Numerical study on a blast mitigation mechanism by a water droplet layer: Validation with experimental results, and the effect of the layer radius

Abstract

This study explored the practicality of a two-phase flow model for water droplets in elucidating the blast mitigation mechanism of water droplets. To validate the model, the numerical data were compared with previous experimental results in terms of the evaporation of a single water droplet, and the interaction between the shock/blast waves and water droplets. Results of the validation confirmed good agreement and consistency between both data by combining the existing models for droplet breakup. Next, the blast-mitigation effect of water droplets sprayed around a high explosive was investigated, where the main parameter was the layer radius. A thicker layer further mitigated the blast wave, but there was a limit to the blast-mitigation effect when the layer radius was greater than a critical value. The high-temperature and high-pressure detonation products should interact with the water droplets, which absorb their momentum and energy. The critical layer radius was equivalent to the dispersion distance of the detonation products. To quantitatively understand the blast-mitigation mechanism of water droplets, the transferred energies by drag force, convective heat transfer, radiative heat transfer, and evaporation were computed. A strong correlation between the blast wave strength and the sum of transferred energies by the drag force and convective heat transfer was obtained in the case that the initial diameter of the water droplets was of the order of millimeters.