In order to investigate the effects of obstacle number on the characteristics of vented gasoline-air mixture explosions

a series of contrast experiments were conducted under three different initial gasoline vapor concentrations in terms of the obstacle number

the conclusions show that: (1) There existed three typical pressure peaks denoted as pv

pmax

and pneg during the gasoline-air mixture explosions in a semi-opened pipe

and the magnitude of pv was just associated with the fracture constant of the polyethylene film at the pipe exit but not with the obstacle number

while the magnitudes of pmax and the absolute values of pneg increased with the growth of obstacle number

and the time to obtain the pmax was not fully dependent on the obstacle number. (2) During the initial flame propagation process

the flame remained a “finger-like” shape

while disturbed by the obstacles

the flame fronts became distorted

and they were accelerated to change from laminar flame to turbulent flame. And finally the flame fronts formed a “mushroom-like” shape outside the pipe

and the more obstacles

the more significant the “mushroom-like” shape. (3) The obstacles had significant effects on the flame acceleration

and the maximum flame speeds increased with the growth of the obstacle number. (4) Overpressure and flame propagation of the explosion process of gasoline-air mixture explosions had a positive feedback coupling relationship between incentives

they promoted with each other during the evolution of explosions

and the coupling relation became more significant with the growth of obstacle number. (5) The effects of obstacle number on the enhancement of pmax and maximum flame speeds for initial gasoline vapor concentrations of 1.3% and 2.1% were more obvious than that of 1.7%.