Study of Attenuation Effect of Water Droplets on Shockwaves from Hydrogen Explosion

The increasing demand for renewable energy storage may position hydrogen as one of the major players in the future energy system. However, to introduce such technology, high level of safety must be offered. In particular, for the accident scenarios with combustion or explosion of the unintendedly released hydrogen in partially or fully confined volumes, such as e.g., road tunnel, the effective countermeasures preventing or reducing the risk of equipment damages and person injuries should be established. A mitigation strategy could be the use of existing fire suppression system, which can inject water as a spray. The shock waves resulted from hydrogen explosion could be weakened by the water droplets met on the shock path. In the presented work an attenuation effect of water droplets presence on the strength of the passing shock was studied. The analysis of the different attenuation mechanisms was performed and estimation of the effect of spray parameters, such as droplet size and spray density, on the shock wave was carried out. For the quantitative evaluation of the attenuation potential, a numerical model for the COM3D combustion code was developed. The novel model for the droplet behavior accounting for the realistic correlations for the fluid (water) particle drag force linked with the corresponding droplet breakup model describing droplet atomization is presented. The model was validated against literature experimental data and was used for the blind simulations of the hydrogen test facility in KIT.