Gas explosions in
coal mines have occurred occasionally,
which
may cause casualties and economic losses. In the actual mine roadway,
the gas concentration distribution is uneven because the gas density
is lower than that of air. Gas explosion characteristics of uneven
gas distribution with the concentration gradient in mine roadways
were analyzed by using the open-source computational fluid dynamic
code OpenFOAM. The flame and pressure characteristics were calculated,
and the flame and shock wave propagation laws of the non-uniform gas–air
mixture explosion with different concentration gradients were analyzed
and compared with the uniform gas–air mixture gas. The results
show that when the overall gas concentration is the same, the flame
velocity and the pressure growth rate of the uniform gas explosion
are lower than those of the non-uniform, but the pressure peaks of
both are similar. At the same time, when the initial volume concentration
is 10%, the non-uniform gas explosion has the highest flame propagation
velocity and peak value. The peak explosion pressure of different
concentration gradients is proportional to the initial concentration.
The above studies clarified the characteristics of gas–air
mixture explosions with concentration gradients and provided theoretical
support for the prevention and control of gas explosion disasters.