To investigate the effect of obstacle position and oil-gas concentration on characteristics of gasoline-air mixture explosion

a series of contrast experiments were conducted under the condition of three different initial gasoline vapor concentrations (1.3%

1.7% and 2.1%) and different obstacle positions. The main observed results are:(1) Three typical peak values are observed in gasoline-air mixture explosion. The peak value of pressure relief pv is independent of obstacle position

while the maximum absolute value of negative pressure peak pneg is obtained when the dimensionless distance between the obstacle and the igniter head Li/L=0.4. In the condition of 2.1% concentration

the peak value of maximum overpressure pmax is obtained at Li/L=0.4

while under the condition of 1.3% concentration

it is obtained at Li/L=0.6. (2) The maximum values of average pressure boost rate (dp/dt)ave

index of explosive power Emax

maximum pressure boost rate (dp/dt)max and maximum explosion index Kmax are all obtained at Li/L=0.4 under the condition of three initial concentrations. (3) During the initial flame propagation process

it presents a “finger-like” shape

while after disturbance by obstacles

the flame fronts produce irregular deformations

a mushroom like flame is formed outside the pipe. When Li/L=0.2

mushroom like flames are most pronounced. (4) The maximum flame propagation velocity Sfmax is obtained at Li/L=0.2 which monotonously decreases with the increase of Li/L from 0.2 to 0.8. Above observation results show that both location of obstacles and initial oil gas concentration have an influence on the characteristic parameters of the gas explosion in the pipeline with built-in obstacles.