Experimental investigation on the effect of a barrier wall on unconfined hydrogen explosion.

27 m3 unconfined hydrogen explosion experiments are conducted to investigate the effect of barrier wall on explosion characteristics. The results show that the flame propagation velocity is highly related with the development of the flame instability, not only dependent on the laminar burning velocity. In front of the wall, due to the wave reflection, the overpressure peak P max and positive overpressure impulse I P increase while the positive overpressure duration time t dur decreases. In the rear of the wall, due to the wave diffraction, P max and I P decrease while t dur increases. The time reaching overpressure peak t peak increases on both sides of the wall. P max is about twice the incident overpressure on the wall surface because of the pressure reflection. The enhancement or mitigation effect of the barrier wall only works in a certain range. The mitigation effect is highly related with the relative height between gas cloud and barrier wall. [Display omitted] • The effect of a barrier wall is analyzed in 27 m3 hydrogen cloud explosion. • The explosion intensity is enhanced before the wall and mitigated behind the wall. • Positive overpressure duration time rises before the wall and drops behind the wall. • The times reaching overpressure peak are delayed on both sides of the wall. • The mitigation effect of the barrier wall with different height is discussed. [ABSTRACT FROM AUTHOR]