Hydrogen diffusion and deflagration characteristics in a closed battery compartment: experimental and numerical simulation investigation

The hydrogen diffusion and deflagration characteristics in different ignition positions in a closed battery compartment are systematically researched with experimental and numerical simulation methods, analyzing the hydrogen deflagration flame propagation process, flame propagation velocity, deflagration overpressure, and deflagration temperature. The results show that the maximum concentration gradient between the compartment top and compartment bottom is 4.9%. A nearly spherical flame is first formed after ignition, and the fireball expansion process is restricted by the compartment wall surface and gradually deformed to form a finger-shaped flame. The flame propagation velocity increases with time. And the flame front position increases slowly and then rapidly. In addition, the flame propagates upward from the bottom slightly faster than the flame propagates downward. The deflagration overpressure in ignition position S2 (the top corner of the compartment) is higher compared to that in ignition position S1 (the top center of the compartment), which is nearly 476 KPa. The rise to deflagration peak overpressure is faster when the ignition position is at the compartment top than that at the compartment bottom. In addition, the ignition position on the closed space side (ignition position S2∼S4) is more dangerous.