Numerical analysis on characteristics and dynamics of gas flow in confined hydrogen-air explosion

Gas flow influences flame morphology and flame propagation. Resorting to large eddy simulation, this paper analyzes flow characteristics and dynamics of confined hydrogen-air explosion. The results reveal that the gas at flame surface accelerates, then decelerates, and finally reversely accelerates. The variation can be contributed to transition from pressure-induced acceleration to deceleration effects. With initial pressure increasing, the decelerating effect has stronger intensity and wider influencing area. With initial turbulent fluctuation velocity increasing, intensity and influencing scope of the decelerating effect rise under higher initial pressure. In unburnt zone, forward gas flow is dominated by accelerating effect of pressure for equivalence ratios of 1.0 and 2.0. In burnt zone, gas flow is alternately dominated by accelerating and decelerating effects of pressure gradient. Vortex appear after flame surface and is largest near flame wrinkles. Formation of the strongest vorticity is dominated by baroclinic torque which represent Rayleigh Taylor instability.