Dispersion of evaporating droplets in the passenger compartment of high-speed train

The outbreak of airborne disease has raised increasing public concern over the cross-infection phenomenon in public transport. This research carried out preliminary investigation on the transport profile of droplets in high-speed train's compartment cabin through an experimentally verified numerical simulation approach. The influence of initial releasing location and initial diameter on the spatial distribution of droplet group is systematically studied. The results show that, for droplets with same initial diameter, under engineering passenger compartment design and standard ventilation mode, the initial releasing location of droplets has little influence on the evaporation rate. The longitudinal and transverse transport distance of small and medium size droplets (20 μm diameter and 50 μm diameter respectively) in passenger cabin is mainly influenced by their initial releasing location, while the large size droplets (100 μm diameter) will quickly deposit on the ground floor due to dominating gravitational load. Meanwhile, it is found that the return air outlet can significantly influence the spreading profile for droplets released nearby. The numerical model established in this study and research outcome can serve as an important reference for proceeding investigations on the infection risk and optimization design of passenger compartment cabin in public transport.