Experimental study of vented hydrogen-air deflagrations in an underground hydrogen refueling station

This study experimentally investigates vented explosions in a scaled model of an underground hydrogen refueling station. The apparatus comprises a 1-L chamber representing the underground storage area, connected to a vertical tower that simulates the passage to the ground surface. A vent at the chamber to tower interface was configured for high static activation pressures P stat to simulate worst-case scenarios. Schlieren imaging captured flame propagation, while the effects of equivalence ratio ϕ , vent area A v , and tower floor area A f on peak pressures were quantified at the chamber and at the tower top. Results show that ϕ strongly influences flame speed and thereby controls the peaks. Changing A v markedly alters internal peaks but only weakly influences tower-top peaks because of the external explosion. A near-linear correlation between the two peaks is observed across conditions, suggesting a simple regression-based estimator for tower-top loads in similar geometries under high P stat .