Flame dynamics in thin semi-closed tubes at different heat loss conditions

The results of detailed 2D numerical simulation of non-steady methane–air flame propagation in semi-closed tubes after ignition near the closed end are presented. Flame dynamics dependence on the tubes width for adiabatic and non-adiabatic walls is obtained. It is shown that main mechanism of front acceleration is flame surface perturbation due to hydrodynamic drag near the walls, which grows due to gas thermal expansion and flow acceleration. The mechanism of vortex formation in vicinity of the front bow point is demonstrated. The vortex is generated at the flame front velocities of the order of Sl ∼ 20 m/s and may become precursor for flow turbulization at later instants.