Experimental study on the combined effect of hydrogen storage tanks and ventilation grilles on the deflagration mechanism in hydrogen-powered ships

Abstract

To explore the coupled effects of ventilation grille openings and hydrogen storage tank arrangements on the consequences of premixed hydrogen deflagration accidents, a semi-open 300 × 300 × 900 mm deflagration visualization platform was constructed. Experiments were conducted under varying conditions of hydrogen equivalence ratio, storage tank arrangement, obstacle-ignition distance, and grille opening angle. The experimental conclusions are as follows: when only with the grilles, Helmholtz oscillations occurred at a 0.3 equivalence ratio, while increasing the grille opening angle reduced internal peak overpressure (P_int) at 0.4 and 0.5 equivalence ratios. As the equivalence ratio increases, high-frequency oscillation duration shortens. Only with hydrogen storage unit obstacles, the deflagration venting peak overpressure (P_out) and three external peak overpressures (P_ext1, P_ext2, and P_ext3) appear. Additionally, the flame propagation speed significantly increases. However, higher equivalence ratios, obstacle volume blockage ratios, and obstacle-ignition distance causes P_ext2 to disappear. Additionally, increasing the obstacle-ignition distance causes P_out to rise initially and then fall. With both obstacles and grilles, P_int occurs at a 0° opening angle, while P_out decreases as grille opening angles increase (15°, 30°, and 45°). The results suggest that loosely arranging hydrogen storage tanks and maximizing the grilles opening angle can effectively reduce hydrogen deflagration consequences in the storage cabin.