Abstract: Regarding the problem that electric vehicle fires in confined spaces such as underground garages are prone to triggering a chain combustion reaction, this study established a full-scale model of two vehicles based on FDS. Using heat release rate, ignition time of adjacent vehicle, temperature, and smoke characteristics as indicators, it comparatively analyzed the blocking effects of vehicle distance and fire baffle. The research indicates that simply increasing the distance between vehicles, although it significantly delays the ignition time from 700 s to 950 s, has a limited effect on ultimately cutting off the fire propagation pathways. Due to the heat accumulation effect within confined spaces, high-temperature smoke plumes and intense radiant heat may still trigger rapid chain combustion. In contrast, fire baffle can significantly restructure the path of hot smoke, and their inhibitory effect increases non-linearly with the increase in height. When the height of the baffle increases from 0.4 m to 1.8 m, the ignition time of adjacent vehicle significantly extends from 730 s to 1 120 s; when the height of the baffle is 2.2 m, the baffle forms a critical barrier that cuts off flame entrainment and radiant heat transfer, preventing adjacent vehicle from being ignited. This study confirms that in underground garage scenarios, adding high-positioned baffle is a more efficient prevention and control measure than adjusting distance, providing a scientific basis for fire protection design.

Key words: underground garage, electric vehicle fire, numerical simulation, vehicle distance, fire baffle